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为什么要拨打alert()
弹出undefined
?我猜测,Javascript没有使用我认为是的this
。我怎样才能修复代码,同时仍然使它看起来像非原型继承代码?为什么会员未定义?
<!DOCTYPE html>
<html>
<head><title>Help</title>
<script type="text/javascript">
var Foo = function (myName) {
this.myName = myName;
}
Foo.prototype.sayName = function() {
alert(this.myName);
}
var foo = new Foo("I am foo");
var bar = {
ask: function (fn) {
fn();
}
};
function doIntroductions() {
bar.ask(foo.sayName);
}
</script>
</head>
<body onload="doIntroductions();">
</body>
</html>