确定静态命名的 JavaScript 函数是否存在以防止错误
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Determine if statically named JavaScript function exists to prevent errors
提问by macintosh264
I have a script on my website that calls a staticallynamed function when called:
我的网站上有一个脚本，它在调用时调用静态命名函数：
childLoad();
The childLoad()function is not always defined though it is always called. How can I prevent the script from calling this function if it does not exist?
该childLoad()函数虽然总是被调用，但并不总是被定义。如果该函数不存在，如何防止脚本调用该函数？
回答by Michael Jasper
if ( typeof childLoad == 'function' ) {
childLoad();
}
回答by Joe
You could use short circuit evaluation:
您可以使用短路评估：
childLoad && childLoad();
编辑
('childLoad' in this) && childLoad && childLoad();
This will make sure childLoadcan be referenced, makes sure it's not undefined, then call the function. It doesn't check to make sure it is a function, but I personally feel that is not needed.
这将确保childLoad可以被引用，确保它不是未定义的，然后调用该函数。它不会检查以确保它是一个函数，但我个人认为不需要。
NOTE: thismight not be the context you are referring to if you are using callor apply. It really depends on the rest of your code.
注意：this如果您使用call或，则可能不是您所指的上下文apply。这真的取决于你的代码的其余部分。
回答by Jayendra
if(typeof childLoad == 'function') {
childLoad();
}
回答by Samich
You can simply check:
您可以简单地检查：
if (childLoad)
childLoad()
回答by jcvandan
You could surround it in a try catch!
你可以用try catch包围它！
回答by Mohammed Shafeek
<script>
/* yourfunction */
if(typeof yourfunction == 'function') {
yourfunction();
}
function yourfunction(){
//function code
}
</script>
