Javascript“Uncaught TypeError：object is not a function”相关性问题 [英] Javascript "Uncaught TypeError: object is not a function" associativity question
问题描述
代码如下：
<body>
<a href="javascript:;" id="test">hello</a>
</body>
<script type="text/javascript">
document.getElementById("test").addEventListener("click", function () {
test()
}, false)
function test() {
var postTypes = new Array('hello', 'there')
(function() { alert('hello there') })()
}
</script>
这将抛出：
未捕获的TypeError：对象不是函数
"Uncaught TypeError: object is not a function"
如果我将匿名函数调用/调用包装在另一个函数中一组括号它将执行警报，但仍然给我一个错误。如果我在var postTypes定义之后放置一个分号，那么它将完全正常。
If I wrap the anonymous function call/invocation in another set of parentheses it will execute the alert, but still give me an error. If I put a semi-colon after the "var postTypes" definition then it will completely fine.
我被认为javascript不需要分号，所以我猜测有一些奇怪的函数应用关联规则我还没有完全理解。为什么我会收到此错误？
I was led to believe that javascript does not require semi-colons, so I'm making a guess that there is some weird associativity rules of function application that I am not fully understanding. Why am I getting this error?
推荐答案
Javascript确实需要分号，只是解释会为您插入当代码变为没有它的语法错误时换行符。*
Javascript does require semi-colons, it's just that the interpret will insert it for you on line-breaks when the code becomes syntax-error without it*.
不幸的是，代码
var a = new B(args)(stuff)()
是不语法错误，因此不会插入; 。 （可以运行的一个例子是
is not a syntax error, so no ; will be inserted. (An example which can run is
var answer = new Function("x", "return x")(function(){return 42;})();
为了避免这样的惊喜，训练自己总是结束声明; 。
To avoid surprises like this, train yourself to always end a statement with ;.
（*：只是一个拇指规则。并非总是如此。插入规则很多更复杂。有关分号插入的博客页面有更多详细信息。）
(*: Just a thumb-rule. Not always true. The insertion rule is much more complicated. This blog page about semicolon insertion has more detail.)
这篇关于Javascript“Uncaught TypeError：object is not a function”相关性问题的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
