toNumber.js #1

define(['./isArray'], function (isArray) {

    /**
     * covert value into number if numeric
     */
    function toNumber(val){
        // numberic values should come first because of -0
        if (typeof val === 'number') return val;
        // we want all falsy values (besides -0) to return zero to avoid
        // headaches
        if (!val) return 0;
        if (typeof val === 'string') return parseFloat(val);
        // arrays are edge cases. `Number([4]) === 4`
        if (isArray(val)) return NaN;
        return Number(val);
    }

    return toNumber;

});