Converts a javascript number from scientific notation to a decimal string

scientificToDecimal.js

var scientificToDecimal = function (num) {
    var nsign = Math.sign(num);
    //remove the sign
    num = Math.abs(num);
    //if the number is in scientific notation remove it
    if (/\d+\.?\d*e[\+\-]*\d+/i.test(num)) {
        var zero = '0',
                parts = String(num).toLowerCase().split('e'), //split into coeff and exponent
                e = parts.pop(), //store the exponential part
                l = Math.abs(e), //get the number of zeros
                sign = e / l,
                coeff_array = parts[0].split('.');
        if (sign === -1) {
            l = l - coeff_array[0].length;
            if (l < 0) {
              num = coeff_array[0].slice(0, l) + '.' + coeff_array[0].slice(l) + (coeff_array.length === 2 ? coeff_array[1] : '');
            } 
            else {
              num = zero + '.' + new Array(l + 1).join(zero) + coeff_array.join('');
            }
        } 
        else {
            var dec = coeff_array[1];
            if (dec)
                l = l - dec.length;
            if (l < 0) {
              num = coeff_array[0] + dec.slice(0, l) + '.' + dec.slice(l);
            } else {
              num = coeff_array.join('') + new Array(l + 1).join(zero);
            }
        }
    }

    return nsign < 0 ? '-'+num : num;
};

tests.js

var expect = function(value) {
    return {
        toEqual: function(otherValue) {
            if(value !== otherValue) {
                console.error(value+' did not yield the correct result!');
            }
        }
    };
};

expect(scientificToDecimal(2.5e25)).toEqual('25000000000000000000000000');
expect(scientificToDecimal(-1.123e-10)).toEqual('-0.0000000001123');
expect(scientificToDecimal(-1e-3)).toEqual('-0.001');
expect(scientificToDecimal(-1.2e-2)).toEqual('-0.012');
expect(scientificToDecimal(12.12)).toEqual(12.12);
expect(scientificToDecimal(141120000000000000)).toEqual(141120000000000000);
expect(scientificToDecimal('0')).toEqual(0);
expect(scientificToDecimal(1.23423534e-12)).toEqual(0.00000000000123423534);