{
  "api": {
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        "mdn_url": "https://developer.mozilla.org/docs/Web/API/CustomElementRegistry",
        "support": {
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          },
          "chrome_android": {
            "version_added": "54"
          },
          "edge": {
            "version_added": false,
            "notes": "<a href='https://developer.microsoft.com/en-us/microsoft-edge/platform/status/customelements/'>In Development</a>"
          },
          "edge_mobile": {
            "version_added": false,
            "notes": "<a href='https://developer.microsoft.com/en-us/microsoft-edge/platform/status/customelements/'>In Development</a>"
          },
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            {
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            },
            {
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                },
                {
                  "type": "preference",
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                }
              ]
            }
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                  "value_to_set": "true"
                }
              ]
            },
            {
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              "flags": [
                {
                  "type": "preference",
                  "name": "dom.webcomponents.enabled",
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                },
                {
                  "type": "preference",
                  "name": "dom.webcomponents.customelements.enabled",
                  "value_to_set": "true"
                }
              ]
            }
          ],
          "ie": {
            "version_added": false
          },
          "opera": {
            "version_added": "41"
          },
          "opera_android": {
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          },
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          },
          "safari_ios": {
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          },
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          },
          "webview_android": {
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          }
        },
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          "standard_track": true,
          "deprecated": false
        }
      },
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        "__compat": {
          "description": "Customized built-in element support",
          "support": {
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              "version_added": "66"
            },
            "chrome_android": {
              "version_added": "66"
            },
            "edge": {
              "version_added": false
            },
            "edge_mobile": {
              "version_added": false
            },
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                "version_added": "63"
              },
              {
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                "version_removed": "63",
                "flags": [
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                    "type": "preference",
                    "name": "dom.webcomponents.customelements.enabled",
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                  }
                ]
              },
              {
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                "version_removed": "59",
                "flags": [
                  {
                    "type": "preference",
                    "name": "dom.webcomponents.enabled",
                    "value_to_set": "true"
                  },
                  {
                    "type": "preference",
                    "name": "dom.webcomponents.customelements.enabled",
                    "value_to_set": "true"
                  }
                ]
              }
            ],
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              },
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                "flags": [
                  {
                    "type": "preference",
                    "name": "dom.webcomponents.customelements.enabled",
                    "value_to_set": "true"
                  }
                ]
              },
              {
                "version_added": true,
                "version_removed": "59",
                "flags": [
                  {
                    "type": "preference",
                    "name": "dom.webcomponents.enabled",
                    "value_to_set": "true"
                  },
                  {
                    "type": "preference",
                    "name": "dom.webcomponents.customelements.enabled",
                    "value_to_set": "true"
                  }
                ]
              }
            ],
            "ie": {
              "version_added": false
            },
            "opera": {
              "version_added": "53"
            },
            "opera_android": {
              "version_added": "53"
            },
            "safari": {
              "version_added": false
            },
            "safari_ios": {
              "version_added": false
            },
            "samsunginternet_android": {
              "version_added": false
            },
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            }
          },
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            "standard_track": true,
            "deprecated": false
          }
        }
      },
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                "notes": "Support for 'Customized built-in elements' as well."
              },
              {
                "version_added": "54",
                "notes": "Support for 'Autonomous custom elements' only."
              }
            ],
            "chrome_android": [
              {
                "version_added": "66",
                "notes": "Support for 'Customized built-in elements' as well."
              },
              {
                "version_added": "54",
                "notes": "Support for 'Autonomous custom elements' only."
              }
            ],
            "edge": {
              "version_added": false,
              "notes": "<a href='https://developer.microsoft.com/en-us/microsoft-edge/platform/status/customelements/'>In Development</a>"
            },
            "edge_mobile": {
              "version_added": false,
              "notes": "<a href='https://developer.microsoft.com/en-us/microsoft-edge/platform/status/customelements/'>In Development</a>"
            },
            "firefox": [
              {
                "version_added": "63"
              },
              {
                "version_added": "59",
                "version_removed": "63",
                "flags": [
                  {
                    "type": "preference",
                    "name": "dom.webcomponents.customelements.enabled",
                    "value_to_set": "true"
                  }
                ]
              },
              {
                "version_added": true,
                "version_removed": "59",
                "flags": [
                  {
                    "type": "preference",
                    "name": "dom.webcomponents.enabled",
                    "value_to_set": "true"
                  },
                  {
                    "type": "preference",
                    "name": "dom.webcomponents.customelements.enabled",
                    "value_to_set": "true"
                  }
                ]
              }
            ],
            "firefox_android": [
              {
                "version_added": "63"
              },
              {
                "version_added": "59",
                "version_removed": "63",
                "flags": [
                  {
                    "type": "preference",
                    "name": "dom.webcomponents.customelements.enabled",
                    "value_to_set": "true"
                  }
                ]
              },
              {
                "version_added": true,
                "version_removed": "59",
                "flags": [
                  {
                    "type": "preference",
                    "name": "dom.webcomponents.enabled",
                    "value_to_set": "true"
                  },
                  {
                    "type": "preference",
                    "name": "dom.webcomponents.customelements.enabled",
                    "value_to_set": "true"
                  }
                ]
              }
            ],
            "ie": {
              "version_added": false
            },
            "opera": [
              {
                "version_added": "53",
                "notes": "Support for 'Customized built-in elements' as well."
              },
              {
                "version_added": "41",
                "notes": "Support for 'Autonomous custom elements' only."
              }
            ],
            "opera_android": [
              {
                "version_added": "53",
                "notes": "Support for 'Customized built-in elements' as well."
              },
              {
                "version_added": "41",
                "notes": "Support for 'Autonomous custom elements' only."
              }
            ],
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              "notes": "Supports 'Autonomous custom elements' but not 'Customized built-in elements'"
            },
            "safari_ios": {
              "version_added": "10.1",
              "notes": "Supports 'Autonomous custom elements' but not 'Customized built-in elements'"
            },
            "samsunginternet_android": {
              "notes": "Support for 'Autonomous custom elements' only.",
              "version_added": "6.0"
            },
            "webview_android": [
              {
                "version_added": "66",
                "notes": "Support for 'Customized built-in elements' as well."
              },
              {
                "version_added": "54",
                "notes": "Support for 'Autonomous custom elements' only."
              }
            ]
          },
          "status": {
            "experimental": true,
            "standard_track": true,
            "deprecated": false
          }
        }
      },
      "get": {
        "__compat": {
          "mdn_url": "https://developer.mozilla.org/docs/Web/API/CustomElementRegistry/get",
          "support": {
            "chrome": [
              {
                "version_added": "66",
                "notes": "Support for 'Customized built-in elements' as well."
              },
              {
                "version_added": "54",
                "notes": "Support for 'Autonomous custom elements' only."
              }
            ],
            "chrome_android": [
              {
                "version_added": "66",
                "notes": "Support for 'Customized built-in elements' as well."
              },
              {
                "version_added": "54",
                "notes": "Support for 'Autonomous custom elements' only."
              }
            ],
            "edge": {
              "version_added": false,
              "notes": "<a href='https://developer.microsoft.com/en-us/microsoft-edge/platform/status/customelements/'>In Development</a>"
            },
            "edge_mobile": {
              "version_added": false,
              "notes": "<a href='https://developer.microsoft.com/en-us/microsoft-edge/platform/status/customelements/'>In Development</a>"
            },
            "firefox": [
              {
                "version_added": "63"
              },
              {
                "version_added": "59",
                "version_removed": "63",
                "flags": [
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                    "type": "preference",
                    "name": "dom.webcomponents.customelements.enabled",
                    "value_to_set": "true"
                  }
                ]
              },
              {
                "version_added": true,
                "version_removed": "59",
                "flags": [
                  {
                    "type": "preference",
                    "name": "dom.webcomponents.enabled",
                    "value_to_set": "true"
                  },
                  {
                    "type": "preference",
                    "name": "dom.webcomponents.customelements.enabled",
                    "value_to_set": "true"
                  }
                ]
              }
            ],
            "firefox_android": [
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              },
              {
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                "version_removed": "63",
                "flags": [
                  {
                    "type": "preference",
                    "name": "dom.webcomponents.customelements.enabled",
                    "value_to_set": "true"
                  }
                ]
              },
              {
                "version_added": true,
                "version_removed": "59",
                "flags": [
                  {
                    "type": "preference",
                    "name": "dom.webcomponents.enabled",
                    "value_to_set": "true"
                  },
                  {
                    "type": "preference",
                    "name": "dom.webcomponents.customelements.enabled",
                    "value_to_set": "true"
                  }
                ]
              }
            ],
            "ie": {
              "version_added": false
            },
            "opera": [
              {
                "version_added": "53",
                "notes": "Support for 'Customized built-in elements' as well."
              },
              {
                "version_added": "41",
                "notes": "Support for 'Autonomous custom elements' only."
              }
            ],
            "opera_android": [
              {
                "version_added": "53",
                "notes": "Support for 'Customized built-in elements' as well."
              },
              {
                "version_added": "41",
                "notes": "Support for 'Autonomous custom elements' only."
              }
            ],
            "safari": {
              "version_added": "10.1",
              "notes": "Supports 'Autonomous custom elements' but not 'Customized built-in elements'"
            },
            "safari_ios": {
              "version_added": "10.1",
              "notes": "Supports 'Autonomous custom elements' but not 'Customized built-in elements'"
            },
            "samsunginternet_android": {
              "notes": "Support for 'Autonomous custom elements' only.",
              "version_added": "6.0"
            },
            "webview_android": [
              {
                "version_added": "66",
                "notes": "Support for 'Customized built-in elements' as well."
              },
              {
                "version_added": "54",
                "notes": "Support for 'Autonomous custom elements' only."
              }
            ]
          },
          "status": {
            "experimental": true,
            "standard_track": true,
            "deprecated": false
          }
        }
      },
      "upgrade": {
        "__compat": {
          "mdn_url": "https://developer.mozilla.org/docs/Web/API/CustomElementRegistry/upgrade",
          "support": {
            "chrome": {
              "version_added": "68"
            },
            "chrome_android": {
              "version_added": "68"
            },
            "edge": {
              "version_added": null
            },
            "edge_mobile": {
              "version_added": null
            },
            "firefox": {
              "version_added": "63"
            },
            "firefox_android": {
              "version_added": "63"
            },
            "ie": {
              "version_added": null
            },
            "opera": {
              "version_added": "55"
            },
            "opera_android": {
              "version_added": "55"
            },
            "safari": {
              "version_added": null
            },
            "safari_ios": {
              "version_added": null
            },
            "samsunginternet_android": {
              "version_added": null
            },
            "webview_android": {
              "version_added": "68"
            }
          },
          "status": {
            "experimental": true,
            "standard_track": true,
            "deprecated": false
          }
        }
      },
      "whenDefined": {
        "__compat": {
          "mdn_url": "https://developer.mozilla.org/docs/Web/API/CustomElementRegistry/whenDefined",
          "support": {
            "chrome": [
              {
                "version_added": "66",
                "notes": "Support for 'Customized built-in elements' as well."
              },
              {
                "version_added": "54",
                "notes": "Support for 'Autonomous custom elements' only."
              }
            ],
            "chrome_android": [
              {
                "version_added": "66",
                "notes": "Support for 'Customized built-in elements' as well."
              },
              {
                "version_added": "54",
                "notes": "Support for 'Autonomous custom elements' only."
              }
            ],
            "edge": {
              "version_added": false,
              "notes": "<a href='https://developer.microsoft.com/en-us/microsoft-edge/platform/status/customelements/'>In Development</a>"
            },
            "edge_mobile": {
              "version_added": false,
              "notes": "<a href='https://developer.microsoft.com/en-us/microsoft-edge/platform/status/customelements/'>In Development</a>"
            },
            "firefox": [
              {
                "version_added": "63"
              },
              {
                "version_added": "59",
                "version_removed": "63",
                "flags": [
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                    "type": "preference",
                    "name": "dom.webcomponents.customelements.enabled",
                    "value_to_set": "true"
                  }
                ]
              },
              {
                "version_added": true,
                "version_removed": "59",
                "flags": [
                  {
                    "type": "preference",
                    "name": "dom.webcomponents.enabled",
                    "value_to_set": "true"
                  },
                  {
                    "type": "preference",
                    "name": "dom.webcomponents.customelements.enabled",
                    "value_to_set": "true"
                  }
                ]
              }
            ],
            "firefox_android": [
              {
                "version_added": "63"
              },
              {
                "version_added": "59",
                "version_removed": "63",
                "flags": [
                  {
                    "type": "preference",
                    "name": "dom.webcomponents.customelements.enabled",
                    "value_to_set": "true"
                  }
                ]
              },
              {
                "version_added": true,
                "version_removed": "59",
                "flags": [
                  {
                    "type": "preference",
                    "name": "dom.webcomponents.enabled",
                    "value_to_set": "true"
                  },
                  {
                    "type": "preference",
                    "name": "dom.webcomponents.customelements.enabled",
                    "value_to_set": "true"
                  }
                ]
              }
            ],
            "ie": {
              "version_added": false
            },
            "opera": [
              {
                "version_added": "53",
                "notes": "Support for 'Customized built-in elements' as well."
              },
              {
                "version_added": "41",
                "notes": "Support for 'Autonomous custom elements' only."
              }
            ],
            "opera_android": [
              {
                "version_added": "53",
                "notes": "Support for 'Customized built-in elements' as well."
              },
              {
                "version_added": "41",
                "notes": "Support for 'Autonomous custom elements' only."
              }
            ],
            "safari": {
              "version_added": "10.1",
              "notes": "Supports 'Autonomous custom elements' but not 'Customized built-in elements'"
            },
            "safari_ios": {
              "version_added": "10.1",
              "notes": "Supports 'Autonomous custom elements' but not 'Customized built-in elements'"
            },
            "samsunginternet_android": {
              "notes": "Support for 'Autonomous custom elements' only.",
              "version_added": "6.0"
            },
            "webview_android": [
              {
                "version_added": "66",
                "notes": "Support for 'Customized built-in elements' as well."
              },
              {
                "version_added": "54",
                "notes": "Support for 'Autonomous custom elements' only."
              }
            ]
          },
          "status": {
            "experimental": true,
            "standard_track": true,
            "deprecated": false
          }
        }
      }
    }
  }
}