如何包装jQuery函数

Question

Question

I'd like to know the best way I can wrap the jQuery function while retaining all functionality. Essentially I want to call $('#someId') but have it operate as $('#' + id + 'someId') by wrapping the function, modifying the arguments, and passing it through to the original jQuery function.

Motivation

I have a section of JS that will reuse the same variable winId which is concatenated and passed to jQuery. Instead of writing

$('#' + winId + 'someId').html();
$('#' + winId + 'someOtherId').css();
...
$('#' + winId + 'someThirdId').text();

throughout the whole file, I want to wrap the jQuery function so I can just call

$('#someId').html();
$('#someOtherId').css();
...
$('#someThirdId').text();

and and have winId added in before passing through to $ .

---

My attempt

Here's what I'm thinking as a wrapper:

(function() {
    var fn = $;

    return $ = function() {
       for ( var i = 0; i < arguments.length; i++ ) {
          if ( typeof arguments[i] == 'string') {
             arguments[i] = /* code to add in winId, omitted */
          }
       }
       return fn.apply( this, arguments );
    }
})();

This works great, except that obviously none of the methods like $.ajax are available:

Uncaught TypeError: Object function () {
    for ( var i = 0; i < arguments.length; i++ ) {
       if ( typeof arguments[i] == 'string' ) {
          arguments[i] = /* code to add in winId, omitted */
       }
    }
    return fn.apply( this, arguments );
} has no method 'ajax' 

Note: I know I could copy the object over using jQuery.extend($, jQuery) , but I'm interested in a more elegant solution than that if possible.

Answer 1

Here's a different implementation:

DEMO

(jQuery.fn.init = (function (init) {

    return function (selector) {
        if (typeof selector === 'string' && selector[0] === '#') {
            arguments[0] = selector.replace('#', '#prefix_');
        }

        return init.apply(this, arguments);
    };

})(jQuery.fn.init)).prototype = jQuery.fn;


$(function () {
    console.log($('#test').length);
    console.log($.ajax);
});

EDIT: Followup question: How can I apply this only within a closure? For example, within an object.

Perhaps with functions that allows to add named decorators and remove them, something like:

HTML

<div id="prefix_test"></div>

JS

var decJQ = (function (decJQ, $) {
    var decorators = {},
        init = $.fn.init;

    ($.fn.init = function () {

        for (var k in decorators) {
            if (decorators.hasOwnProperty(k)) {
                arguments = decorators[k].apply(this, arguments);
            }
        }

        return init.apply(this, arguments);
    }).prototype = $.fn;

    return $.extend(decJQ, {
        decorate: function (name, fn) {
            decorators[name] = fn;
        },
        undecorate: function (name) {
            delete decorators[name];
        }
    });

})(window.decJQ || {}, jQuery);

decJQ.decorate('idPrefix', function (selector) {
    if (typeof selector === 'string' && selector[0] === '#') {
        arguments[0] = selector.replace('#', '#prefix_');
    }

    return arguments;
});

$(function () {
    console.log($('#test').length); //1

    decJQ.undecorate('idPrefix');

    console.log($('#test').length); //0
});

EDIT 2: You could also go for something extremely simple, such as:

(function ($) {
    //use $ which has been wrapped
})(function () {
    //do some manipulations
    return jQuery.apply(this, arguments);
});

Answer 2

Following the suggestion by Bergi and the post he links to here , this is one way to go:

$.fn.extend({
    initCore: $.fn.init,
    init: function (selector, context, rootjQuery) {
        if (typeof selector === 'string' && selector[0] === '#') {
            selector = selector.replace('#', '#' + winId);
        }
        return $.fn.initCore(selector, context, rootjQuery);
    }
});

$.fn.init.prototype = $.fn;

I've tested $('#foo') will find a div that has a winId prefixed to the id value, like this <div id="1foo"></div> .

For example: http://jsfiddle.net/MfdJS/1/

Answer 3

Add class="winID" to your elements.

Use $(".winID").find('#someId").css(...) to access CSS attributes of specific element.

Use $(".winID").css(...) to access CSS attribues to all winID tagged elements.

Answer 4

ok well i just tested

$('.con'+'tainer')

and

$('d'+'iv');

and

var s = 't';
$('.con'+s+'ainer');

and the console is returning the correct values

i belive that you are calling a function jQuery() with a string parameter, so as long as you use the normal syntax for building/appending/constructing a string with the plus signs, i think you're golden. im glad you asked this question because now i know too

Answer 5

That's a pretty strange thing to do. Why don't you just create a CSS selector string for winId and save it as a variable?

var foo = '#' + winId;

Now you can do:

$(foo + ', #bar').html("add some content"); 

What you're proposing to do will leave any programmer working on this project -- including you six months from now -- completely flummoxed when they use $('#bar') and it's actually selecting #foo and #bar.