I'm trying to create a simple, small and basic javascript framework just for learning purposes.
But the thing is that i'm allready stuck at the very basics.
I'm trying to do something like this:
$('testdiv').testFunction();
And the code i've written for that:
var elementID;
var smallFramework = {
$:function(id) {
this.elementID = id;
},
testFunction:function() {
alert(this.elementID);
}
};
window.$ = smallFramework.$;
But in return I get:
$('testdiv) is undefined
Can anyone help me with this small and hopefully easy question?
To get the behavior you're expecting, you need the $ function to return an object with a method named testFunction.
Try:
var smallFramework = // an object for namespacing
{
$:function(id) // the core function - returns an object wrapping the id
{
return { // return an object literal
elementID: id, // holding the id passed in
testFunction: function() // and a simple method
{
alert(this.elementID);
}
};
}
};
Of course, there are many other ways to achieve the behavior you desire.
If you're trying to add methods to an HTML element you could do something along these lines.
$ = function( elementId ) {
var element = document.getElementById( elementId );
element.testFunction = function(){
alert( this.id );
return this; // for chaining
}
return element;
}
$('test').testFunction();
Try
smallFramework.$('testdiv');
instead. According to the code you posted, that's where your $ function ended up.
Or alternatively, it looks like you're trying to replicate something like jQuery. You might want to try something like this.
var $ = smallFramework = (function () {
var f =
{
find:function(id) {
f.elementID = id;
return f; //every function should return f, for chaining to work
},
testFunction:function() {
alert(f.elementID);
return f;
}
}
return f.find //the find function will be assigned to $.
//and also assigned to smallFramework.
//the find function returns f, so you get access to testFunction via chaining
// like $("blah").testFunction()
})() //note this function gets called immediately.
this code may look confusing to someone new to JavaScript because it depends heavily on the concept of closures. I suggest that if this doesn't make sense, spend some time at Douglas Crockford's JavaScript website. This is important because the code above will bite if you happen to use this in the find function because this won't be bound to f, as you may expect it to be when you use it from $ or smallFramework.
Related
I'm trying to create a javascript library like jquery. I get how to create a normal library like so:
var lib=lib||(function () {
function privateFunction (alert ("hi");){};
return {
exampleAlert: function(input){
alert(input);
}
}
})();
Calling it like so:
lib.exampleAlert ("test");
This is like jquery
$.ajax(stuffhere);
My question revolves around jquery. It can call the dom like $('.class').hide() and have functions like $.ajax(stuffhere); in the same library. How can I do dom calls and a regular function call like the ajax one in the above example library?
Thanks in advance!! Have searched more days than I would like to admit.
DOM has nothing to do here, it is just up to jQuery implementation.
If you ask about having both lib() and lib.func() calls, then you can do the following to support both function types at the same time:
var lib = function(sel) {
return {
object: document.querySelector(sel),
text: function(val) {
if (val === undefined) {
return this.object.innerText;
} else {
this.object.innerText = val;
}
}
};
};
lib.ajax = function() {
console.log("AJAX imitation");
};
Now, you can do both:
lib("body").text("hi"); // jQuery-style setter
var text = lib("body").text(); // jQuery-style getter, returns "hi"
and
lib.ajax();
jQuery works exactly in the same way, but hundred times more complex.
I'd like to 'proxy' (not sure if that's the term at all) a function inside a function object for easy calling.
Given the following code
function Soldier() {
this.el = $("<div></div>").addClass('soldier');
this.pos = this.el.position; // $(".soldier").position(), or so I thought
}
In the console:
s = new Soldier();
$("#gamemap").append(s.el); // Add the soldier to the game field
s.pos === s.el.position // this returns true
s.el.position() // Returns Object {top: 0, left: 0}
s.pos() // Returns 'undefined'
What am I doing wrong in this scenario and is there an easy way to achieve my goal (s.pos() to return the result of s.el.position()) ?
I thought about s.pos = function() { return s.el.position(); } but looks a bit ugly and not apropriate. Also I'd like to add more similar functions and the library will become quite big to even load.
When you're calling s.pos(), its this context is lost.
You can simulate this behavior using call():
s.pos.call(s); // same as s.pos()
s.pos.call(s.el); // same as s.el.position()
This code is actually ok:
s.pos = function() { return s.el.position(); }
An alternative is using bind():
s.pos = s.el.position.bind(el);
You can use the prototype, that way the functions will not be created separately for every object:
Soldier.prototype.pos = function(){ return this.el.position(); }
I'd recommend to use the prototype:
Soldier.prototype.pos = function() { return this.el.position(); };
Not ugly at all, and quite performant actually.
If you want to directly assign it in the constructor, you'll need to notice that the this context of a s.pos() invocation would be wrong. You therefore would need to bind it:
…
this.pos = this.el.position.bind(this.el);
It's because the context of execution for position method has changed. If you bind the method to work inside the element context it will work.
JS Fiddle
function Soldier() {
this.el = $("<div></div>").addClass('soldier');
this.pos = this.el.position.bind(this.el);
}
var s = new Soldier();
$("#gamemap").append(s.el);
console.log(s.pos());
This is some JS code
var methodArr = ['firstFunc','secondFunc','thirdFunc'];
for(var i in methodArr)
{
window[methodName] = function()
{
console.log(methodName);
}
}
My problem is that how to get the name of a function in JS.
In JS, use this.callee.name.toString() can get the function name. But in this situation, it is a null value. How can i get the 'funName' string?
Sorry, I didn't make it clear.
I want to create functions in a for loop, all these functions has almost the same implementation which need its name. But others can call these functions use different name.I want to know what methodName function is called.
it seems a scope problem.
Try this:
var methodArr = ['firstFunc','secondFunc','thirdFunc'];
for(var i in methodArr) {
var methodName = methodArr[i]; // <---- this line missed in your code?
window[methodName] = (function(methodName) {
return function() {
console.log(methodName);
}
})(methodName);
}
window['secondFunc'](); // output: secondFunc
well i'm confuse about the line witch says "$.Recup ..." I don't know why it is named the same as the plugin name and what it's for.
(function ($) {
$.fn.Recup = function () {
var parametros = {
};
var tsic = true;
$.Recup = function (opciones) {
var Metodos = {
};
return Metodos;
};
$.Recup.anterior = function () {
};
$.Recup.siguiente = function () {
}
})(jQuery);
I'm refering to this code, What does $.Recup exactly do?it would be perfect if someone gives me an example please
$.Recup = function (opciones) {
var Metodos = {
};
return Metodos;
};
In this case it appears to be a questionable plugin design - especially since $.Recup is not assigned until $.fn.Recup is first called.
However, if it is "appropriately and/or well written" is another question that requires context of (intended) usage. For what it is worth, I would reject this code as written as it smells of misunderstood design and widely scoped side-effects.
Anyway, the way the function is assigned determines how the method can be called.
// let $ be jQuery, then:
$.fn.foo = function () { console.log("foo") }
$.bar = function () { console.log("bar") }
$.foo() // TypeError: $.foo is not a function
$.bar() // -> "bar"
$("sel").foo() // -> "foo"
$("sel").bar() // TypeError: $(..).bar is not a function
That is, $.fn.foo is like .each() - it does something based on the currently selected elements (which are represented by this). On the other hand, $.bar is like jQuery.each() - it provides a way to iterate over a general collection but is not related to a specific set of (previously) selected elements.
In general, a plugin should only add a single entry to $.fn, but directly adding to $ may be useful to expose utility functions - it should definitely be done with care.
Here are two approaches that fix the issue of incorrectly leaked data:
$.fn.Recup = function () {
var parametros = ..
var tsic = true;
// Most trivial change; then use recup in this scope
// (or child scopes) only. There is no $.Recup - yay!
var recup = function (opciones) {
};
// ..
}
Or, just expose as local methods:
$.fn.Recup = function () {
var parametros = ..
var tsic = true;
function anterior () {
}
function siguiente () {
}
// Just use simple functions in scope
}
This is a jQuery plugin.
jQuery.fn is an alias to jQuery's prototype. So this line lets you call the Recup function on instances of jQuery :
$('#myid').Recup();
Here's the documentation on creating jQuery plugins.
I used a code:
jQuery.fn.MyFunction = function(){
return this.each(function() {
attributes = "test";
return attributes;
});}
But when I call
var1 = $(this).MyFunction();alert(var1);
I got an [object], but not the "test".
How to allow jquery plugin return a some value?
jQuery plugins are generally designed to return a jQuery object so you can chain method calls:
jQuery("test").method1().method2() ...
If you want to return something else, use the following syntax:
jQuery.fn.extend({
myFunction: function( args ) {
attributes = "test";
return attributes;
}
});
, or access it via its index using [].
Here is once again your code:
jQuery.fn.MyFunction = function() { #1
return this.each(function() { #2
return "abc"; #3
}); #4
}; #5
Now let's check what every line do.
We declare property MyFunction which is a function for every jQuery object.
This line is first and the last statement of jQuery.MyFunction(). We return the result of this.each(), not the result of lambda-function (used as a argument for jQuery.each()). And this.each() returns itself so the final result is that you get jQuery object returned.
Lines 3-5 are not important in fact.
Just consider those two examples:
jQuery.fn.MyFunction = function() {
return this.each(function() {
return "abc";
});
};
jQuery.fn.AnotherFunction = function() {
return "Hello World";
};
var MyFunctionResult = $(document).MyFunction();
var AnotherFunctionResult = $(document).AnotherFunction();
alert(MyFunctionResult);
alert(AnotherFunctionResult);
I believe jQuery returns the object, so you can maintain the chainability of diffrent functions.
Hmm, perhaps use
var1 = $(this)[0].MyFunction();alert(var1);
But I'm not sure if that is what you want or if your code works at all. What are you trying to achieve? Are you sure you want to call this.each()?
Like the others said, jQuery returns jQuery objects in most cases, and accessing the actual object can be accomplished using an indexer [] or the get method.