重複の可能性:
イベント関数パラメーターとしての現在の要素
これは機能しますか
<script type="text/javascript">
var foo = function(param)
{
param.innerHTML = "Not a button";
};
</script>
<button onclick="foo(this)" id="bar">Button</button>
これよりも？
<script type="text/javascript">
var foo = function()
{
document.getElementId("bar").innerHTML = "Not a button";
};
</script>
<button onclick="foo()" id="bar">Button</button>
また、最初の方法では、他の場所から JavaScript を読み込んで、任意のページ要素に対してアクションを実行できますか?
The code that you have would work, but is executed from the global context, which means that this refers to the global object.
<script type="text/javascript">
var foo = function(param) {
param.innerHTML = "Not a button";
};
</script>
<button onclick="foo(this)" id="bar">Button</button>
You can also use the non-inline alternative, which attached to and executed from the specific element context which allows you to access the element from this.
<script type="text/javascript">
document.getElementById('bar').onclick = function() {
this.innerHTML = "Not a button";
};
</script>
<button id="bar">Button</button>
ええ、最初のメソッドは、idに関係なく常にターゲット要素を取得するため、他の場所から呼び出されたすべての要素で機能します。
このフィドルをチェックしてください
In JavaScript this always refers to the “owner” of the function we're executing, or rather, to the object that a function is a method of. When we define our faithful function doSomething() in a page, its owner is the page, or rather, the window object (or global object) of JavaScript.