Selection.setBaseAndExtent()

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句法
范例
规范
浏览器兼容性
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这是实验性技术
检查浏览器兼容性表格要小心谨慎在生产中使用这之前。

setBaseAndExtent() 方法在 Selection interface sets the selection to be a range including all or parts of two specified DOM nodes, and any content located between them.

句法

sel.setBaseAndExtent(anchorNode,anchorOffset,focusNode,focusOffset)

参数

anchorNode
anchorOffset
focusNode
focusOffset

注意 : If the focus position appears before the anchor position in the document, the direction of the selection is reversed — the caret is placed at the beginning of the text rather the end, which matters for any keyboard command that might follow. For example, Shift + ➡︎ would cause the selection to narrow from the beginning rather than grow at the end.

返回值

Void.

异常

若 anchorOffset is larger than the number of child nodes inside anchorNode ，或者若 focusOffset is larger than the number of child nodes inside focusNode ， IndexSizeError exception is thrown.

范例

In this example, we have two paragraphs containing spans, each one containing a single word. The first one is set as the anchorNode and the second is set as the focusNode . We also have an additional paragraph that sits in between the two nodes.

Next, we have two form inputs that allow you to set the anchorOffset and focusOffset — they both have a default value of 0.

We also have a button that when pressed invokes a function that runs the setBaseAndExtent() method with the specified offsets, and copies the selection into the output paragraph at the very bottom of the HTML.

<h1>setBaseAndExtent example</h1>
<div>
  <p class="one"><span>Fish</span><span>Dog</span><span>Cat</span><span>Bird</span></p>
  <p>MIDDLE</p>
  <p class="two"><span>Car</span><span>Bike</span><span>Boat</span><span>Plane</span></p>
</div>
<div>
  <p>
    <label for="aOffset">Anchor offset</label>
    <input id="aOffset" name="aOffset" type="number" value="0">
  </p>
  <p>
    <label for="fOffset">Focus offset</label>
    <input id="fOffset" name="fOffset" type="number" value="0">
  </p>
  <p><button>Capture selection</button></p>
</div>
<p><strong>Output</strong>: <span class="output"></span></p>

The JavaScript looks like so:

var one = document.querySelector('.one');
var two = document.querySelector('.two');
var aOffset = document.getElementById('aOffset');
var fOffset = document.getElementById('fOffset');
var button = document.querySelector('button');
var output = document.querySelector('.output');
var selection;
button.onclick = function() {
  try {
    selection = document.getSelection();
    selection.setBaseAndExtent(one, aOffset.value, two, fOffset.value);
    var text = selection.toString();
    output.textContent = text;
  } catch(e) {
    output.textContent = e.message;
  }
}

Play with the live example below, setting different offset values to see how this affects the selection.

注意 : You can find this example on GitHub ( see it live also )。

规范

规范	状态	注释
选定 API The definition of 'Selection.setBaseAndExtent()' in that specification.	工作草案

浏览器兼容性

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. 更新 GitHub 上的兼容性数据

	桌面						移动
	Chrome	Edge	Firefox	Internet Explorer	Opera	Safari	Android webview	Chrome for Android	Firefox for Android	Opera for Android	Safari on iOS	Samsung Internet
`setBaseAndExtent`	Chrome Yes	Edge 12	Firefox 53	IE ?	Opera Yes	Safari Yes	WebView Android Yes	Chrome Android Yes	Firefox Android 53	Opera Android Yes	Safari iOS Yes	Samsung Internet Android Yes

图例

完整支持
兼容性未知 ?
实验。期望将来行为有所改变。

另请参阅

Selection

元数据

最后修改： Mar 18, 2019

DOM (文档对象模型)
Selection
特性
方法
1. addRange()
2. collapse()
3. collapseToEnd()
4. collapseToStart()
5. containsNode()
6. deleteFromDocument()
7. extend()
8. getRangeAt()
9. modify()
10. removeAllRanges()
11. removeRange()
12. selectAllChildren()
13. setBaseAndExtent()
14. toString()
DOM 相关页面

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句法

参数

返回值

异常

范例

规范

浏览器兼容性

图例

另请参阅

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