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how to properly call functions in prototype in js

How do I properly call the functions inside pretest?
I get this error: Uncaught TypeError: b.testmenow is not a function
var pretest = function () {
var MAX_NUM = 250.0;
var prebase = function (NEW_NUM) {
this.NEW_NUM = NEW_NUM ? NEW_NUM : true;
};
prebase.prototype.testmenow = function () {
return this.NEW_NUM;
};
return prebase;
};
var b = new pretest(111);
console.log(b.testmenow());

You need to accept your input into new pretest(111) by adding n.
And then you must instantiate your prebase constructor using n.
var pretest = function (n) {
var MAX_NUM = 250.0;
var prebase = function (NEW_NUM) {
this.NEW_NUM = NEW_NUM ? NEW_NUM : true;
};
prebase.prototype.testmenow = function () {
return this.NEW_NUM;
};
return new prebase(n);
};
var b = pretest(111);
console.log(b.testmenow());
It is strange that you have two constructors here, you can surely do this with one.
As Felix has deftly mentioned, you can call pretest(111) instead of new pretest(111).

javascript - how to take selected element from function and pass it through as a parameter of another function

I have been trying for days upon weeks with trying to build a personal library without jQuery for my school club, and so far I am hitting a rut when it comes to passing through an element or objects through to another function. The notation I am trying for is this :
CC(function(){
CC('id:wrapper').set('html','Hello World!');
});
That is my test code, and the library looks as it does below:
"use strict";
var CC = function () {
var args = arguments[0] || {};
if(typeof args === "object") {
args = args || {};
}
else if(typeof args === "function") {
args = arguments[0];
return window.onload = args;
}
else if(typeof args !== "object" || typeof args !== "function") {
var elem = get(args);
return elem;
}
};
CC({
//Can only be done once. Will return TypeError because '$' won't exist afterward
noConflict : function (name) {
name = new CC();
return name;
}
});
//The way to modify things
CC.mod = CC.prototype = {};
CC.extend = CC.mod.extend = function () {
var args = arguments[0] || {};
var target = get(args);
return target;
};
CC.mod.extend({
//Use psuedo types to set specific values (required)
set : function(type, value) {
return set(this.target, type, value);
}
});
//General get function to get selectors, generate functions, or return values
function get() {
var args = arguments[0] || {};
//Check if the argument is a function
//If it is, return the function on page load
if (typeof args === "function") {
return window.onload = args;
}
//Check argument type
if(typeof args !== "object") {
args = arguments[0];
return args;
}
else {
args = {};
return args;
}
//Check if args has an elem psuedo
if(args.indexOf("id:") > -1 || args.indexOf("class:") > -1 || args.indexOf("tag:") > -1) {
var target = args;
//Run id psuedo
if(target.indexOf("id:") > -1) {
target = target.replace('id:','');
console.log(target);
return document.getElementById(target);
}
//Run class psuedo
else if(target.indexOf("class:") > -1) {
target = target.replace('class:','');
console.log(target);
return document.getElementsByClassName(target);
}
//Run tag psuedo
else if(target.indexOf("tag:") > -1) {
target = target.replace('class:','');
console.log(target);
return document.getElementsByTagName(target);
}
}
//Check if args is not null
//If not, then return args value
if(args !== null) {
return args.value;
}
else {
return null;
}
}
//General function to set things for elements
function set(elem, property, value) {
//If the element provided is part of getting an element
//If it is, run the psuedo checker
if(elem.indexOf("id:") > -1 || elem.indexOf("class:") > -1 || elem.indexOf("tag:") > -1) {
elem = get(elem);
//Rerun the set() function to set properties and values
set(elem, property, value);
}
//If not, then run the type psuedo checker
else {
//Check if style
if(property.indexOf("css:") > -1 || property.indexOf("style:") > -1) {
//Check for the independent types
if(property.indexOf("css:") > -1) {
property = property.replace('css:','');
return elem.style[property] = value;
}
else if(property.indexOf("style:") > -1) {
property = property.replace('style:','');
return elem.style[property] = value;
}
}
//Check if attribute
else if(property.indexOf("attr:") > -1) {
property = property.replace('attr:','');
return elem.setAttribute(property, value);
}
//Check if html
else if(property.indexOf("html") > -1) {
return elem.innerHTML = value;
}
//To add more, just add another else if(condition...) {Code} statement
//Condition must be defined in psuedo selectors
//Condition must be property.indexOf("selector:" > -1)
//return statement must consist of a return value from the value parameter
}
}
I don't know how to get my methods to pass through correctly and I don't know how to get my methods to apply to the element in the CC('id:wrapper') code. I already have the 'psuedo selector' made to get rid of the id: code. Any help would be much appreciated!

You've posted quite some code which I wasn't able to get to work quickly, so I'm not sure if this will help you out.
The basic idea is that your CC method will always have to return an object with a set method. If there's no element with id="wrapper", you'll have to figure out a way to handle exceptions.
You can use bind to create a new function from an earlier defined function with a pre-bound this context and pre-filled in arguments.
A simplified example:
var CC = function(query) {
return {
set: set.bind(null, document.querySelector(query))
};
}
function set(element, attr, val) {
element.setAttribute(attr, val);
}
CC("input").set("placeholder", "I was set by js");
<input type="text" />
If you want to do more advanced binding of arguments, I'd suggest you google "Currying". With some code, you can make functions automatically return new functions when called with less arguments than needed.
What .bind does:
The bind method is defined in Function.prototype. You can call it on any function you've defined to create a new function.
The first argument that goes in to bind, is used as the this context in the newly created function. You could, for example, do:
var myDiv = document.querySelector("div");
var logText = function() {
console.log(this.innerText);
};
var logDivText = logText.bind(myDiv);
logText(); // Bound to window, logs undefined
logDivText(); // Bound to div, logs text
<div>Text in a div</div>
Any other arguments passed to bind, are automatically passed as arguments. For example:
var sum = function(a, b) {
return a + b;
};
var sum3 = sum.bind(null, 3); // we don't use this, so we don't define it
console.log(sum3(5)); // Prints 8

Get object caller name by function call JavaScript

I'm writing a piece of code to easily save error logs in an object for debugging.
What I'm trying to achieve is to get the Object name from the function it was called from like so:
var MainObject = {
test : function() {
return MainObject.test.caller;
// When called from MainObject.testcaller,
// it should return MainObject.testcaller.
},
testcaller : function() {
return MainObject.test(); // Should return MainObject.testcaller, Returns own function code.
},
anothercaller : function() {
return MainObject.test(); // Should return MainObject.anothercaller, Returns own function code.
}
}
However when I run this code it returns the function code from MainObject.testcaller.
JSFiddle example
Is there any way this is possible?
Update
After looking at Rhumborl's answer, I discovered that assigning the value through another function would lead it to point back at the function name without the object itself.
Code:
(function (name, func) {
MainObject[name] = func;
})('invalid', function() {
return MainObject.test("blah");
});
// This now points at invalid() rather than MainObject.invalid()
Updated fiddle

There is a non–standard caller property of functions that returns the caller function, however that is a pointer to a function object and doesn't tell you the object it was called as a method of, or the object's name. You can get a reference to the function through arguments.callee.
There is also the obsolete arguments.caller, but don't use that. It also provides a reference to the calling function (where supported).
Once you have a reference to the calling function (if there is one), you then have the issue of resolving its name. Given that Functions are Objects, and objects can be referenced by multiple properties and variables, the concept of a function having a particular name is alluvial.
However, if you know that the function is a property of some object, you can iterate over the object's own enumerable properties to find out which one it is.
But that seems to be a rather odd thing to do. What are you actually trying to do? You may be trying to solve a problem that can be worked around in a much more robust and simpler way.
Edit
You can do what you want in a very limited way using the method described above for the case in the OP, however it is not robust or a general solution:
var mainObject = {
test : function() {
var obj = this;
var caller = arguments.callee.caller;
var global = (function(){return this}());
var fnName, objName;
for (var p in global) {
if (global[p] === obj) {
objName = p;
}
}
for (var f in obj) {
if (obj[f] === caller) {
fnName = f;
}
}
return objName + '.' + fnName;
},
testcaller : function() {
return mainObject.test();
},
anothercaller : function() {
return mainObject.test();
}
}
console.log(mainObject.testcaller()); // mainObject.testcaller
console.log(mainObject.anothercaller()); // mainObject.anothercaller
but it's brittle:
var a = mainObject.anothercaller;
console.log(a()); // mainObject.anothercaller
var b = {
foo : mainObject.anothercaller
}
console.log(b.foo()); // mainObject.anothercaller
Oops.

You can use this trick at http://www.eriwen.com/javascript/js-stack-trace/ which throws an error, then parses the stack trace.
I have updated it for the latest versions of Firefox, Chrome and IE. Unfortunately it doesn't work well on my IE9 (and I haven't tested it on Opera).
function getStackTrace() {
var callstack = [];
var isCallstackPopulated = false;
try {
i.dont.exist += 0; //doesn't exist- that's the point
} catch (e) {
if (e.stack) { //Firefox/Chrome/IE11
var lines = e.stack.split('\n');
for (var i = 0, len = lines.length; i < len; i++) {
var line = lines[i].trim();
if (line.match(/^at [A-Za-z0-9\.\-_\$]+\s*\(/)) {
// Chrome/IE: " at Object.MainObject.testcaller (url:line:char)"
var entry = line.substring(3, line.indexOf('(') - 1);
// Chrome appends "Object." to the front of the object functions, so strip it off
if (entry.indexOf("Object.") == 0) {
entry = entry.substr(7, entry.length);
}
callstack.push(entry);
} else if (line.match(/^[A-Za-z0-9\.\-_\$]+\s*#/)) {
// Firefox: "MainObject.testcaller#url:line:char"
callstack.push(line.substring(0, lines[i].indexOf('#')));
}
}
//Remove call to getStackTrace()
callstack.shift();
isCallstackPopulated = true;
} else if (window.opera && e.message) { //Opera
var lines = e.message.split('\n');
for (var i = 0, len = lines.length; i < len; i++) {
if (lines[i].match(/^\s*[A-Za-z0-9\-_\$]+\(/)) {
var entry = lines[i];
//Append next line also since it has the file info
if (lines[i + 1]) {
entry += lines[i + 1];
i++;
}
callstack.push(entry);
}
}
//Remove call to getStackTrace()
callstack.shift();
isCallstackPopulated = true;
}
}
if (!isCallstackPopulated) { //IE9 and Safari
var currentFunction = arguments.callee.caller;
while (currentFunction) {
var fn = currentFunction.toString();
var fname = fn.substring(fn.indexOf("function") + 8, fn.indexOf('')) || 'anonymous';
callstack.push(fname);
currentFunction = currentFunction.caller;
}
}
return callstack;
}
var MainObject = {
test: function (x) {
// first entry is the current function (test), second entry is the caller
var stackTrace = getStackTrace();
var caller = stackTrace[1];
return caller + "()";
},
testcaller: function () {
return MainObject.test(1, null);
}
}
function SomeFunction() {
return MainObject.test("blah");
}
document.body.innerHTML += '<b style="color: red">' + MainObject.testcaller() + '</b>';
document.body.innerHTML += '<div>Calling SomeFunction() returns: <b style="color: red">' + SomeFunction() + '</b></div>';
MainObject.test() should return: <b style="color: blue">MainObject.testcaller()</b>
<hr />
MainObject.test() returns:
Updated fiddle here

Closure multiplate call function im javascript

Example i write down
myFunc('asdas')
It's console.log me
'asdas'
Then after i write down
myFunc('as')('ds')('ko')....('other')
function must console.log me
"as ds ko .... other"
I tried do realize this but have many problems with it.
function me (str){
//var temp = str;
return function mes(val) {
val += ' '+ str;
console.log(val);
//return mes;
}
}
How correctly realize this function?

Well, this is a bit funny, but works:
concat = function(x, val) {
val = (val || "") + x;
var p = function(y) { return concat(y, val) };
p.toString = function() { return val };
return p
}
x = concat('a')('b')('c')('d');
document.write(x)

You can generate multiple console logs and chain it like this:
function me(str) {
console.log(str);
return me; // or whatever you called the function
}
me(1)(2)(3);
As far as I'm aware though, there's no way for the function to know when it should be outputting if you're just chaining, though.
The best option I can think of would be this:
function me(str) {
me.str = me.str || ''; // make sure me.str is set
// set me.write if this is the first call to me()
me.write = me.write || function() {
console.log(me.str);
}
me.str += (me.str.length ? ' ' : '') + str; // add a space if needed
return me; // or whatever you called the function
}
me(1)(2)(3).write();

Super in Backbone

When I override the clone() method of a Backbone.Model, is there a way to call this overriden method from my implantation? Something like this:
var MyModel = Backbone.Model.extend({
clone: function(){
super.clone();//calling the original clone method
}
})

You'll want to use:
Backbone.Model.prototype.clone.call(this);
This will call the original clone() method from Backbone.Model with the context of this(The current model).
From Backbone docs:
Brief aside on super: JavaScript does not provide a simple way to call
super — the function of the same name defined higher on the prototype
chain. If you override a core function like set, or save, and you want
to invoke the parent object's implementation, you'll have to
explicitly call it.
var Note = Backbone.Model.extend({
set: function(attributes, options) {
Backbone.Model.prototype.set.apply(this, arguments);
...
}
});

You can also use the __super__ property which is a reference to the parent class prototype:
var MyModel = Backbone.Model.extend({
clone: function(){
MyModel.__super__.clone.call(this);
}
});

Josh Nielsen found an elegant solution for this, which hides a lot of the ugliness.
Just add this snippet to your app to extend Backbone's model:
Backbone.Model.prototype._super = function(funcName){
return this.constructor.prototype[funcName].apply(this, _.rest(arguments));
}
Then use it like this:
Model = Backbone.model.extend({
set: function(arg){
// your code here
// call the super class function
this._super('set', arg);
}
});

Working from the answers given by geek_dave and charlysisto, I wrote this to add this._super(funcName, ...) support in classes that have multiple levels of inheritance. It's worked well in my code.
Backbone.View.prototype._super = Backbone.Model.prototype._super = function(funcName) {
// Find the scope of the caller.
var scope = null;
var scan = this.__proto__;
search: while (scope == null && scan != null) {
var names = Object.getOwnPropertyNames(scan);
for (var i = 0; i < names.length; i++) {
if (scan[names[i]] === arguments.callee.caller) {
scope = scan;
break search;
}
}
scan = scan.constructor.__super__;
}
return scan.constructor.__super__[funcName].apply(this, _.rest(arguments));
};
A year later I've fixed some bugs and made things faster. Below is the code that I use now.
var superCache = {};
// Hack "super" functionality into backbone.
Backbone.View.prototype._superFn = Backbone.Model.prototype._superFn = function(funcName, _caller) {
var caller = _caller == null ? arguments.callee.caller : _caller;
// Find the scope of the caller.
var scope = null;
var scan = this.__proto__;
var className = scan.constructor.className;
if (className != null) {
var result = superCache[className + ":" + funcName];
if (result != null) {
for (var i = 0; i < result.length; i++) {
if (result[i].caller === caller) {
return result[i].fn;
}
}
}
}
search: while (scope == null && scan != null) {
var names = Object.getOwnPropertyNames(scan);
for (var i = 0; i < names.length; i++) {
if (scan[names[i]] === caller) {
scope = scan;
break search;
}
}
scan = scan.constructor.__super__;
}
var result = scan.constructor.__super__[funcName];
if (className != null) {
var entry = superCache[className + ":" + funcName];
if (entry == null) {
entry = [];
superCache[className + ":" + funcName] = entry;
}
entry.push({
caller: caller,
fn: result
});
}
return result;
};
Backbone.View.prototype._super = Backbone.Model.prototype._super = function(funcName) {
var args = new Array(arguments.length - 1);
for (var i = 0; i < args.length; i++) {
args[i] = arguments[i + 1];
}
return this._superFn(funcName, arguments.callee.caller).apply(this, args);
};
Then given this code:
var A = Backbone.Model.extend({
// className: "A",
go1: function() { console.log("A1"); },
go2: function() { console.log("A2"); },
});
var B = A.extend({
// className: "B",
go2: function() { this._super("go2"); console.log("B2"); },
});
var C = B.extend({
// className: "C",
go1: function() { this._super("go1"); console.log("C1"); },
go2: function() { this._super("go2"); console.log("C2"); }
});
var c = new C();
c.go1();
c.go2();
The output in the console is this:
A1
C1
A2
B2
C2
What's interesting is that class C's call to this._super("go1") scans the class hierarchy until it gets a hit in class A. Other solutions do not do this.
P.S. Uncomment the className entries of the class definitions to enable caching of the _super lookup. (The assumption is that these class names will be unique in the application.)

If you want just to call this._super(); without passing the function name as an argument
Backbone.Controller.prototype._super = function(){
var fn = Backbone.Controller.prototype._super.caller, funcName;
$.each(this, function (propName, prop) {
if (prop == fn) {
funcName = propName;
}
});
return this.constructor.__super__[funcName].apply(this, _.rest(arguments));
}
Better use this plugin:
https://github.com/lukasolson/Backbone-Super

I believe you can cache the original method (although not tested):
var MyModel = Backbone.Model.extend({
origclone: Backbone.Model.clone,
clone: function(){
origclone();//calling the original clone method
}
});

backbone._super.js, from my gists: https://gist.github.com/sarink/a3cf3f08c17691395edf
// Forked/modified from: https://gist.github.com/maxbrunsfeld/1542120
// This method gives you an easier way of calling super when you're using Backbone in plain javascript.
// It lets you avoid writing the constructor's name multiple times.
// You still have to specify the name of the method.
//
// So, instead of having to write:
//
// var Animal = Backbone.Model.extend({
// word: "",
// say: function() {
// return "I say " + this.word;
// }
// });
// var Cow = Animal.extend({
// word: "moo",
// say: function() {
// return Animal.prototype.say.apply(this, arguments) + "!!!"
// }
// });
//
//
// You get to write:
//
// var Animal = Backbone.Model.extend({
// word: "",
// say: function() {
// return "I say " + this.word;
// }
// });
// var Cow = Animal.extend({
// word: "moo",
// say: function() {
// return this._super("say", arguments) + "!!!"
// }
// });
(function(root, factory) {
if (typeof define === "function" && define.amd) {
define(["underscore", "backbone"], function(_, Backbone) {
return factory(_, Backbone);
});
}
else if (typeof exports !== "undefined") {
var _ = require("underscore");
var Backbone = require("backbone");
module.exports = factory(_, Backbone);
}
else {
factory(root._, root.Backbone);
}
}(this, function(_, Backbone) {
"use strict";
// Finds the next object up the prototype chain that has a different implementation of the method.
var findSuper = function(methodName, childObject) {
var object = childObject;
while (object[methodName] === childObject[methodName]) {
object = object.constructor.__super__;
}
return object;
};
var _super = function(methodName) {
// Keep track of how far up the prototype chain we have traversed, in order to handle nested calls to `_super`.
this.__superCallObjects__ || (this.__superCallObjects__ = {});
var currentObject = this.__superCallObjects__[methodName] || this;
var parentObject = findSuper(methodName, currentObject);
this.__superCallObjects__[methodName] = parentObject;
// If `methodName` is a function, call it with `this` as the context and `args` as the arguments, if it's an object, simply return it.
var args = _.tail(arguments);
var result = (_.isFunction(parentObject[methodName])) ? parentObject[methodName].apply(this, args) : parentObject[methodName];
delete this.__superCallObjects__[methodName];
return result;
};
// Mix in to Backbone classes
_.each(["Model", "Collection", "View", "Router"], function(klass) {
Backbone[klass].prototype._super = _super;
});
return Backbone;
}));

In the case that you don't know what the parent class is exactly (multiple inheritance or you want a helper function) then you can use the following:
var ChildModel = ParentModel.extend({
initialize: function() {
this.__proto__.constructor.__super__.initialize.apply(this, arguments);
// Do child model initialization.
}
});
With helper function:
function parent(instance) {
return instance.__proto__.constructor.__super__;
};
var ChildModel = ParentModel.extend({
initialize: function() {
parent(this).initialize.apply(this, arguments);
// Do child model initialization.
}
});

Pass the parent class as an option during instantiation:
BaseModel = Backbone.Model.extend({
initialize: function(attributes, options) {
var self = this;
this.myModel = new MyModel({parent: self});
}
});
Then in your MyModel you can call parent methods like this
this.options.parent.method();
Keep in mind this creates a retain cycle on the two objects. So to let the garbage collector do it's job you would need to manually destroy the retain on one of the objects when finished with it. If you're application is pretty large. I would encourage you to look more into hierarchal setups so events can travel up to the correct object.

2 functions below, one requires you pass in the function name, the other can "discover" which function we want the super version of
Discover.Model = Backbone.Model.extend({
_super:function(func) {
var proto = this.constructor.__super__;
if (_.isUndefined(proto[func])) {
throw "Invalid super method: " + func + " does not exist in prototype chain.";
}
return proto[func].apply(this, _.rest(arguments));
},
_superElegant:function() {
t = arguments;
var proto = this.constructor.__super__;
var name;
for (name in this) {
if (this[name] === arguments.callee.caller) {
console.log("FOUND IT " + name);
break;
} else {
console.log("NOT IT " + name);
}
}
if (_.isUndefined(proto[name])) {
throw "Super method for: " + name + " does not exist.";
} else {
console.log("Super method for: " + name + " does exist!");
}
return proto[name].apply(this, arguments);
},
});

Here is how I would do this:
ParentClassName.prototype.MethodToInvokeName.apply(this);
so for your example this is:
Model.prototype.clone.apply(this)