How to get an object's methods?

问题:

Is there a method or propertie to get all methods from an object? For example:

function foo() {}
foo.prototype.a = function() {}
foo.prototype.b = function() {}

foo.get_methods(); // returns ['a', 'b'];

UPDATE: Are there any method like that in Jquery?

Thank you.

回答1:

function getMethods(obj)
{
    var res = [];
    for(var m in obj) {
        if(typeof obj[m] == "function") {
            res.push(m)
        }
    }
    return res;
}

回答2:

Remember that technically javascript objects don't have methods. They have properties, some of which may be function objects. That means that you can enumerate the methods in an object just like you can enumerate the properties. This (or something close to this) should work:

var bar
for (bar in foo)
{
    console.log("Foo has property " + bar);
}

There are complications to this because some properties of objects aren't enumerable so you won't be able to find every function on the object.

回答3:

You can use console.dir(object) to write that objects properties to the console.

回答4:

In modern browsers you can use Object.getOwnPropertyNames to get all properties (both enumerable and non-enumerable) on an object. For instance:

function Person ( age, name ) {
    this.age = age;
    this.name = name;
}

Person.prototype.greet = function () {
    return "My name is " + this.name;
};

Person.prototype.age = function () {
    this.age = this.age + 1;
};

// ["constructor", "greet", "age"]
Object.getOwnPropertyNames( Person.prototype );

Note that this only retrieves own-properties, so it will not return properties found elsewhere on the prototype chain. That, however, doesn't appear to be your request so I will assume this approach is sufficient.

If you would only like to see enumerable properties, you can instead use Object.keys. This would return the same collection, minus the non-enumerable constructor property.

回答5:

The methods can be inspected in the prototype chain of the object using the browser's developer tools (F12):

  console.log(yourJSObject);

or more directly

  console.dir(yourJSObject.__proto__);

回答6:

In ES6:

let myObj   = {myFn : function() {}, tamato: true};
let allKeys = Object.keys(myObj);
let fnKeys  = allKeys.filter(key => typeof myObj[key] == 'function');
console.log(fnKeys);
// output: ["myFn"]

回答7:

var funcs = []
for(var name in myObject) {
    if(typeof myObject[name] === 'function') {
        funcs.push(name)
    }
}

I'm on a phone with no semi colons :) but that is the general idea.

回答8:

the best way is:

let methods = Object.getOwnPropertyNames(yourobject);
console.log(methods)

use 'let' only in es6, use 'var' instead

回答9:

var methods = [];
for (var key in foo.prototype) {
    if (typeof foo.prototype[key] === "function") {
         methods.push(key);
    }
}

You can simply loop over the prototype of a constructor and extract all methods.

回答10:

for me, the only reliable way to get the methods of the final extending class, was to do like this:

function getMethodsOf(obj){
  const methods = {}
  Object.getOwnPropertyNames( Object.getPrototypeOf(obj) ).forEach(methodName => {
    methods[methodName] = obj[methodName]
  })
  return methods
}

回答11:

In Chrome is keys(foo.prototype). Returns ["a", "b"].

See: https://developer.chrome.com/devtools/docs/commandline-api#keysobject

Later edit: If you need to copy it quick (for bigger objects), do copy(keys(foo.prototype)) and you will have it in the clipboard.

回答12:

Get the Method Names:

var getMethodNames = function (obj) {
    return (Object.getOwnPropertyNames(obj).filter(function (key) {
        return obj[key] && (typeof obj[key] === "function");
    }));
};

Or, Get the Methods:

var getMethods     = function (obj) {
    return (Object.getOwnPropertyNames(obj).filter(function (key) {
        return obj[key] && (typeof obj[key] === "function");
    })).map(function (key) {
        return obj[key];
    });
};