我正在尝试通过对象方法内部的变量创建对象。像这样的事情:
ObjectFactory = function(){
}
ObjectFactory.prototype.createObject = function(objectName){
return new objectName;
}
var of = new ObjectFactory();
var MyObject = of.createObject('MyObjectClassName');
知道如何做吗？
最佳答案
只需删除引号(并在var后添加一个空格):
var MyObject = of.createObject(MyObjectClassName);
(如果您确实想要使用字符串，请参见下文。)
完整示例:Live Copy
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>Example</title>
<style>
body {
font-family: sans-serif;
}
</style>
</head>
<body>
<script>
(function() {
"use strict";
var ObjectFactory = function(){
};
ObjectFactory.prototype.createObject = function(ctor){
return new ctor;
};
function Foo() {
}
var of = new ObjectFactory();
var f = of.createObject(Foo);
display("<code>f instanceof Foo</code>? " + (f instanceof Foo));
function display(msg) {
var p = document.createElement('p');
p.innerHTML = String(msg);
document.body.appendChild(p);
}
})();
</script>
</body>
</html>
如果您确实需要在那里使用字符串而不是函数引用，那么除非您想使用 eval(通常最好避免)，否则您需要一个对象来查找构造函数函数(例如，从字符串名称获取构造函数)。
如果构造函数是全局，您可以在全局对象上查找它们，但全局是一个坏主意。相反，给自己一个 map 对象并将构造函数设置为 map 的属性:
var constructorMap = {
MyObjectClassName: MyObjectClassName
};
您甚至可以将其放在“ObjectFactory”上:
ObjectFactory.constructorMap = {
MyObjectClassName: MyObjectClassName
};
然后
ObjectFactory.prototype.createObject = function(objectName){
return new ObjectFactory.constructorMap[objectName];
};
完整示例:Live Copy
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>Example</title>
<style>
body {
font-family: sans-serif;
}
</style>
</head>
<body>
<script>
(function() {
"use strict";
function Foo() {
}
var ObjectFactory = function(){
};
ObjectFactory.constructorMap = {
Foo: Foo
};
ObjectFactory.prototype.createObject = function(objectName){
return new ObjectFactory.constructorMap[objectName];
};
var of = new ObjectFactory();
var f = of.createObject("Foo");
display("<code>f instanceof Foo</code>? " + (f instanceof Foo));
function display(msg) {
var p = document.createElement('p');
p.innerHTML = String(msg);
document.body.appendChild(p);
}
})();
</script>
</body>
</html>
关于javascript - 在 JavaScript 对象方法中从变量创建新对象，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/25471520/