# Sort numerical array.

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Hi there!!W3schools has demonstrated how to sort a numerical array using the following code: <code><script type="text/javascript">function sortNumber(a, {return a -b;}var arr = new Array(6);arr[0] = "10";arr[1] = "5";arr[2] = "40";arr[3] = "25";arr[4] = "1000";arr[5] = "1";document.write(arr + "<br />");document.write(arr.sort(sortNumber));</script></code>I just wanted to know how does the sortNumber() function work? What's the meaningful of the a,b parameters which are passed into the function? What are they intended to represent, and how does this snippet: a-b cause to sort the array numerical elements ascending?

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Given any pair of elements in the array, if the return value is positive, A goes after B, if the return value is negative, A goes before B. If the return value is 0 their positions are not changed.

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@ingolme:Thanks you very much about your response, but unfortunately, I didn't understand your words because you spoke too shortly. I didn't understand how does the a and b parameters that passed into the sortNumber() function represent an index in the array. Here they don't use the arr syntax so how can they access to the array's indices?

Edited by atar
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All of it happend inside the Javascript's engine.The sort() method takes the function you gave it and tries it on pairs of elements over and over until all of them are sorted. You tell it which of the pair is supposed to go first an which goes second with the algorithm you have in the function. Just imagine that the array only has two elements, A points to the first element and B points to the last one, you tell it which of the two should go first based on the value that they have.

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