html change 事件

The change event is fired for <input>, <select>, and <textarea> elements when a change to the element‘s value is committed by the user. Unlike the inputevent, the change event is not necessarily fired for each change to an element‘s value.

事件在元素input,select,textarea的内容由用户改变的时候触发，并且不像input事件每一次的改变都触发。

Description

Depending on the kind of form element being changed and the way the user interacts with the element, the change event fires at a different moment:

• When the element is activated (by clicking or using the keyboard) for <input type="radio"> and <input type="checkbox">;

• When the user commits the change explicitly (e.g. by selecting a value from a <select>‘s dropdown with a mouse click, by selecting a date from a date picker for <input type="date">, by selecting a file in the file picker for <input type="file">, etc.);

• When the element loses focus after its value was changed, but not commited (e.g. after editing the value of <textarea> or <input type="text">).

Different browsers do not always agree whether a change event should be fired for certain types of interaction. For example, keyboard navigation in <select>elements never fires a change event in Gecko until the user hits Enter or switches the focus away from the <select> (see bug 126379).

描述

事件触发依赖于元素类型，触发方式以及触发不同时刻，如下所示

• 对于<input type=‘radio‘>和<input type="checkbox">，元素激活时触发（通过点击或者键盘）

• 用户明确提交更改（例如，鼠标点击选取select，从 <input type="date">选取日期，从<input type="file">选取文件）

• 元素失去焦点时内容以改变，但并未提交（例如 <textarea> 或者 <input type="text">）也会触发、

不同的游览器不保证特定类型的交互触发change事件。例如，在Gecko，除非用户点击enter或者从<select>移去焦点，通过键盘选取select将不会触发change事件。

引用：https://developer.mozilla.org/en-US/docs/Web/Events/change

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怪不得很多change事件和预想的不一样。