为什么在调用document.ready()中声明的函数时未定义?

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问题描述

这是我的HTML/JavaScript:

Here is my HTML/JavaScript:

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head><meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>Untitled Document</title>
    <script type="text/javascript" src="/script/jquery.js"></script>
    <script type="text/javascript">
        $(function(){
            var $str = "hello world";

            function foo() {
                alert($str);
            }
        });
    </script>
</head>
<body>
    <form name="statusUpdateForm" method="post">
        <input type="button" name="submitButton" value=" " onclick="foo();" />
    </form>
</body>
</html>

单击按钮时，出现一个JavaScript错误，指出未定义foo.如何调用在document.ready()内部声明的JavaScript函数?

When I click the button, I get a JavaScript error stating that foo is not defined. How can I call a JavaScript function declared inside document.ready()??

推荐答案

基本上，您要将函数的作用域放在另一个函数中.

You're placing the function's scope within another function, basically.

图片:

<script>
  document.onload = function(){
    function foo(){
      alert('bar');
    }
  };
  foo();
</script>

这是您要完成的任务的传真.就像在函数中定义的变量超出其范围之外，函数名称具有相同的特征.

That is the facsimile of what you're trying to accomplish. Just like variables defined within a function are off limits outside of it, function names take on the same characteristics.

侧注 JavaScript不需要在变量名上加上$前缀(尽管就名称而言是可以接受的).我不知道您是否来自PHP，并且已经习惯或意识到了.

Side-Note JavaScript doesn't require $ prefix on variable names (though is acceptable as far as names are concerned). I didn't know if you're coming from PHP and are just accustomed or were aware.

我想将我的评论作为答案.

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