jquery - Array Like Objects in Javascript -

i'm wondering how jquery constructs array-like object. key thing i'm trying work out how manages console interpret array , display such. know has length property, after playing bit can't quite figure out.

i know has no technical advantage on normal array object in example below. think it's important semantic element when users testing , debugging.

a normal array object.

function foo(){     // array objects have length property , it's properties use integer     // based sequential key names, e.g. 0,1,2,3,4,5,6 array.     this.length = 1;     this[0] = 'hello' } // make sure add length property prototype match array  // prototype foo.prototype.length = 0;  // give array object array method test works      foo.prototype.push = array.prototype.push  // create array object  var bar = new foo;  //test  bar.push('world');  console.log(bar); // outputs  { 0: 'hello',   1: 'world',   length: 2,   __proto__: foo } 

where jquery output

var jqarray = $('div')  console.log(jqarray);  // outputs [<div></div>,<div></div>,<div></div>,<div></div>] 

if run

console.dir(jqarray)  // outputs  { 0: htmldivelement,   1: htmldivelement,   2: htmldivelement,   3: htmldivelement,   4: htmldivelement,   context: htmldocument,   length: 5,   __proto__: object[0]  } 

the proto of jquery object interesting since object , not jquery.fn.init expected, [0] indicates when you.

console.dir([]) // outputs array[0] object name or array[x] x being internal length of // array 

i have no idea how jquery has set it's proto object[0] guess answer lies somewhere in there. got ideas?

the object has have length , splice

> var x = {length:2, '0':'foo', '1':'bar', splice:function(){}} > console.log(x); ['foo', 'bar'] 

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and fyi, object[0] prototype same reason. browser seeing prototype array because:

$.prototype.length == 0; $.prototype.splice == [].splice;