each, forEach

jQuery.each( collection, callback(indexInArray, valueOfElement) )

collectionThe object or array to iterate over.

callback(indexInArray, valueOfElement)The function that will be executed on every object.

each 를 쓸때 callback function 에  첫번째 파라미터는 index 값이다. i++ .. 과 같다고 봐도 된다.

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from https://developer.mozilla.org/en/JavaScript/Reference/Global_Objects/Array/forEach

Syntax

array.forEach(callback[, thisArg])

Parameters

callback

Function to execute for each element.

thisArg

Object to use as this when executing callback.

<script>

var arr = ['a','b','c','d','e'];

// item:a/index:0

arr.forEach(function (item,index) {
    alert('item:'+item+'/index:'+index);

});

</script>