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Range.setStartBefore() 方法相对另一个 Node来设置一个Range 的开始位置. Range的开始节点（focusNode）的父节点，和 referenceNode的父节点是同一个.
Syntax
range.setStartBefore(referenceNode);
Parameters
Example
var range = document.createRange();
var referenceNode = document.getElementsByTagName("div").item(0);
range.setStartBefore(referenceNode);
Specifications
| Specification | Status | Comment |
|---|---|---|
| DOM Range.setStartBefore() |
Living Standard | No change. |
| Document Object Model (DOM) Level 2 Traversal and Range Specification Range.setStartBefore() |
Obsolete | Initial specification. |
Browser compatibility
The compatibility table on this page is generated from structured data. If you'd like to contribute to the data, please check out https://github.com/mdn/browser-compat-data and send us a pull request.
Update compatibility data on GitHub
| Desktop | Mobile | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
setStartBefore | Chrome Full support Yes | Edge Full support 12 | Firefox Full support 4 | IE Full support 9 | Opera Full support 9 | Safari Full support Yes | WebView Android Full support Yes | Chrome Android Full support Yes | Edge Mobile Full support Yes | Firefox Android Full support 4 | Opera Android Full support Yes | Safari iOS Full support Yes | Samsung Internet Android ? |
Legend
- Full support
- Full support
- Compatibility unknown
- Compatibility unknown