检查对象属性和调用方法的更好方法

Question

(Sorry if it was queried previously, I didnt found it)

I used to check if an object and method exists and call it in this way:

 obj && obj.method && obj.method()

But, I suspect that some cases this are making some troubles on IE..

Do I need check it using typeof undefined/function/object ?

 typeof obj === 'object' && typeof obj.method === 'function' && obj.method()

I would like to know what is the securest and clearest style to code it.

Answer 1

To ensure that you can properly execute a method named method on an object named object , this is the shortest safe check:

if (typeof object === 'object' && typeof object.method === 'function') {
    object.method();
}

You need to first check that the object exists, then make sure that the property you want is a function. Any other checks are redundant.

Note this falls apart if you have something weird like a number 0 or boolean false with a method property you're trying to execute, but you may have larger problems if you're appending properties to booleans and numbers.