String to jQuery function

Question

Overview

I am trying to find the jQuery function that matches a selection attribute value and run that function on the selection.

Example.

$('[data-store="' + key + '"]').each(function() {
var $callback = $(this).attr('data-filter');
if($callback != null) {
    var fn = window['$.fn.nl2br()'];
    if(jQuery.isFunction(fn)) {
        $(this).fn();
    }
}
$(this).setValue(value);
});

Problem 1

I'm not sure how to create a jQuery function call from string.

I know I can call the function like this, $(this)'onclick'; however I have no way to check if it exists before trying to call it.

Normally I could do this: var strfun = 'onclick'; var fn = body[strfun];

if(typeof fn === 'function') {
    fn();
}

This seems to fail:

var fn = window['$.fn.nl2br()'];
if(jQuery.isFunction(fn)) {
    $(this).fn();
}

EDIT:

I seem to be having success doing this:

if($callback != null) {
    var fn = $(this)[$callback]();
    if( typeof fn === 'function') {
        $(this)[$callback]();
    }
}

Problem 2

Using jQuery.isFunction() how do you check if a methods exists? can you do this with jQuery.isFunction()?

Example

Declare function:

$.fn.nl2br = function() {
    return this.each(function() {
        $(this).val().replace(/(<br>)|(<br \/>)|(<p>)|(<\/p>)/g, "\r\n");
    });
};

Test if function existe, these options fail:

jQuery.isFunction($.fn.nl2br); // = false
jQuery.isFunction($.fn['nl2br']()); //false

I know typeof sometimes returns funny results under IE however I it will work fine for jQuery functions — Levi Putna
– Levi Putna, Commented May 16, 2012 at 5:19

jaredhoyt · Accepted Answer · 2012-05-16 05:19:05Z

4

Functions in JavaScript are referenced through their name just like any other variables. If you define var window.foobar = function() { ... } you should be able to reference the function through window.foobar and window['foobar']. By adding (), you are executing the function.

In your second example, you should be able to reference the function through $.fn['nl2br']:

$.fn.nl2br = function() {
    return this.each(function() {
        $(this).val().replace(/(<br>)|(<br \/>)|(<p>)|(<\/p>)/g, "\r\n");
    });
};

console.log(jQuery.isFunction($.fn['nl2br']));

See a working example - http://jsfiddle.net/jaredhoyt/hXkZK/1/

answered May 16, 2012 at 5:19

jaredhoyt

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1 Comment

Levi Putna Over a year ago

Thanks, I sort of answered my own question after I posted. Funny how that happens. Your answer made my understanding much clearer.

The System Restart · Accepted Answer · 2012-05-16 05:18:56Z

1

var fn = window['$.fn.nl2br']();

and

jQuery.isFunction($.fn['nl2br']);

answered May 16, 2012 at 5:18

The System Restart

2,88121 silver badges28 bronze badges

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