How can one compare string and numeric values (respecting negative values, with null always last)?

Question

I\'m trying to sort an array of values that can be a mixture of numeric or string values (e.g. [10,\"20\",null,\"1\",\"bar\",\"-2\",-3,null,5,\"foo\"]). How can

Answer 1

You should first check to see if either value is null and return the opposite value.

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On a side note:

For your default _order value, you should check if the parameter is undefined instead of comparing its value to null. If you try to compare something that is undefined directly you will get a reference error:

(undefinedVar == null) // ReferenceError: undefinedVar is not defined

Instead, you should check if the variable is undefined:

(typeof undefinedVar == "undefined") // true

Also, it's probably a better idea to wrap your compare function in a closure instead of relying on a global order variable.

Sometime like:

[].sort(function(a, b){ return sort(a, b, order)})

This way you can sort at a per-instance level.

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http://jsfiddle.net/gxFGN/10/

JavaScript

function sort(a, b, asc) {
    var result;

    /* Default ascending order */
    if (typeof asc == "undefined") asc = true;

    if (a === null) return 1;
    if (b === null) return -1;
    if (a === null && b === null) return 0;

    result = a - b;

    if (isNaN(result)) {
        return (asc) ? a.toString().localeCompare(b) : b.toString().localeCompare(a);
    }
    else {
        return (asc) ? result : -result;
    }
}