Javascript 如何判断一个javascript变量是否是一个函数
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how to tell if a javascript variable is a function
提问by Mr Bell
I need to loop over the properties of a javascript object. How can I tell if a property is a function or just a value?
我需要遍历 javascript 对象的属性。如何判断一个属性是一个函数还是一个值？
var model =
{
propertyA: 123,
propertyB: function () { return 456; }
};
for (var property in model)
{
var value;
if(model[property] is function) //how can I tell if it is a function???
value = model[property]();
else
value = model[property];
}
回答by Phrogz
Use the typeofoperator:
使用typeof运算符：
if (typeof model[property] == 'function') ...
Also, note that you should be sure that the properties you are iterating are part of this object, and not inherited as a public property on the prototype of some other object up the inheritance chain:
另外，请注意，您应该确保您正在迭代的属性是此对象的一部分，而不是作为继承链上其他对象原型上的公共属性继承：
for (var property in model){
if (!model.hasOwnProperty(property)) continue;
...
}
回答by Kashyap
Following might be useful to you, I think.
我认为以下内容可能对您有用。
How can I check if a javascript variable is function type?
BTW, I am using following to check for the function.
顺便说一句，我正在使用以下内容来检查该功能。
// Test data
var f1 = function () { alert("test"); }
var o1 = { Name: "Object_1" };
F_est = function () { };
var o2 = new F_est();
// Results
alert(f1 instanceof Function); // true
alert(o1 instanceof Function); // false
alert(o2 instanceof Function); // false
回答by Rintala
You can use the following solution to check if a JavaScript variable is a function:
您可以使用以下解决方案来检查 JavaScript 变量是否为函数：
var model =
{
propertyA: 123,
propertyB: function () { return 456; }
};
for (var property in model)
{
var value;
if(typeof model[property] == 'function') // Like so!
else
value = model[property];
}
