setState：function（）{是什么意思

Question

what does it mean when you set a function like this

setState: function(){  
}

Answer 1

The code is incomplete, but it looks like you're assigning a function as the value to a property called setState of an object that isn't shown in your code.

An example:

var myObject = {
    prop1: 'abc',
    prop2: function() {
       alert('def');
    }
};

Above, I'm creating a variable called myObject that is an object with two properties, prop1 and prop2 . The first one is a string. If I write alert(myObject.prop1) it'll alert "abc".

The second one is a function. If I write myObject.prop2() I'll execute that function, which'll alert "def".

Answer 2

That would appear in the context of an object literal , like this:

var obj = {
    setState: function(){  
    }
};

It assigns the function to the named property of the object. The function is anonymous (it has no name), though the property has a name. You could call the function like so:

obj.setState();

Literal notation is basically a series of propname: value within curly braces ( {} ), separated by commas, where value can be any valid value —a string, a number, a function reference... The property name can appear literally, as in your example, or in quotes ( "propname": value ) if the literal name is a reserved word (eg, you'd need quotes for a property called var since var is a reserved word).