为什么这有效..
<script type="text/javascript">
<!--
function myAlert(){
alert('magic!!!');
}
if(document.addEventListener){
myForm.addEventListener('submit',myAlert,false);
}else{
myForm.attachEvent('onsubmit',myAlert);
}
// -->
</script>
但不是这个???
<script type="text/javascript">
<!--
function myAlert(){
alert('magic!!!');
}
if(document.addEventListener){
myForm.addEventListener('submit',myAlert(),false);
}else{
myForm.attachEvent('onsubmit',myAlert());
}
// -->
</script>
区别在于调用时使用括号myAlert
功能。
我得到的错误..
“htmlfile:类型不匹配。”通过VS2008编译时。
The ()在函数之后意味着execute函数本身并返回它的值。如果没有它,您只需拥有该函数,该函数作为回调传递很有用。
var f1 = function() { return 1; }; // 'f1' holds the function itself, not the value '1'
var f2 = function() { return 1; }(); // 'f2' holds the value '1' because we're executing it with the parenthesis after the function definition
var a = f1(); // we are now executing the function 'f1' which return value will be assigned to 'a'
var b = f2(); // we are executing 'f2' which is the value 1. We can only execute functions so this won't work
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