这是一个实验中的功能
此功能某些浏览器尚在开发中，请参考浏览器兼容性表格以得到在不同浏览器中适合使用的前缀。由于该功能对应的标准文档可能被重新修订，所以在未来版本的浏览器中该功能的语法和行为可能随之改变。
GlobalEventHandlers.onselectstart 表示 selectstart 事件绑定的事件处理器，比如用户在网页上开始选择任意文本内容时触发。
译者注：在输入控件中选择文本时，触发的是控件绑定的 select 事件。
Syntax
obj.onselectstart = function;
Example
document.onselectstart = function() {
console.log("Selection started!");
};
详细用法参见 Key quote generator 示例。
Specifications
| Specification | Status | Comment |
|---|---|---|
| Selection API GlobalEventHandlers.onselectstart |
Working Draft | Initial definition. |
Browser compatibility
We're converting our compatibility data into a machine-readable JSON format.
This compatibility table still uses the old format,
because we haven't yet converted the data it contains.
Find out how you can help!
| Feature | Firefox (Gecko) | Chrome | Internet Explorer | Opera | Safari |
|---|---|---|---|---|---|
| Basic support | 43 (43)[1] 52 (52)[2] |
(Yes) | (Yes) | ? | 1.3 |
| Feature | Firefox Mobile (Gecko) | Android | IE Mobile | Opera Mobile | Safari Mobile |
|---|---|---|---|---|---|
onselectionchange |
43.0 (43)[1] 52.0 (52)[2] |
? | ? | ? | ? |
[1] This is implemented behind the dom.select_events.enabled preference, which defaults to false except on Nightly.
[2] This is now fully enabled on Firefox 52 release version.