import.meta

import.meta object exposes context-specific metadata to a JavaScript module. It contains information about the module, like the module's URL.

句法

import.meta
					

描述

The syntax consists of the keyword import , a dot, and the identifier meta . Normally the left-hand side of the dot is the object on which property access is performed, but here import is not really an object.

import.meta object is created by the ECMAScript implementation, with a null prototype. The object is extensible, and its properties are writable, configurable, and enumerable.

范例

Using import.meta

Given a module my-module.js

<script type="module" src="my-module.js"></script>
					

you can access meta information about the module using the import.meta 对象。

console.log(import.meta); // { url: "file:///home/user/my-module.js" }
					

It returns an object with a url property indicating the base URL of the module. This will either be the URL from which the script was obtained, for external scripts, or the document base URL of the containing document, for inline scripts.

Note that this will include query parameters and/or hash (i.e., following the ? or # ).

For example, with the following HTML:

<script type="module">
import './index.mjs?someURLInfo=5';
</script>
					

..the following JavaScript file will log the ` someURLInfo parameter:

// index.mjs
new URL(import.meta.url).searchParams.get('someURLInfo'); // 5
					

The same applies when a file imports another:

// index.mjs
import './index2.mjs?someURLInfo=5';
// index2.mjs
new URL(import.meta.url).searchParams.get('someURLInfo'); // 5
					

Note that while Node.js will pass on query parameters (or the hash) as in the latter example, as of Node 14.1.0, a URL with query parameters will err when loading in the form node --experimental-modules index.mjs?someURLInfo=5 (it is treated as a file rather than a URL in this context).

Such file-specific argument passing may be complementary to that used in the application-wide location.href (with query strings or hash added after the HTML file path) (or on Node.js, through process.argv ).

规范

规范
import.meta proposal
HTML Living Standard
The definition of 'import.meta' in that specification.

浏览器兼容性

更新 GitHub 上的兼容性数据
Desktop Mobile Server
Chrome Edge Firefox Internet Explorer Opera Safari Android webview Chrome for Android Firefox for Android Opera for Android Safari on iOS Samsung Internet Node.js
import.meta Chrome 64 Edge 79 Firefox 62 IE 不支持 No Opera 51 Safari 11.1 WebView Android 64 Chrome Android 64 Firefox Android 62 Opera Android 47 Safari iOS 12 Samsung Internet Android 9.0 nodejs 10.4.0

图例

完整支持
完整支持
不支持
不支持

实现进度

The following table provides a daily implementation status for this feature, because this feature has not yet reached cross-browser stability. The data is generated by running the relevant feature tests in Test262 , the standard test suite of JavaScript, in the nightly build, or latest release of each browser's JavaScript engine.

另请参阅

Metadata