Parsing and converting exponential values to decimal in JavaScript

Question

I want to parse and convert an exponential value into a decimal using JavaScript. 4.65661287307739E-10 should give 0.000000000465661287307739. What

Answer 1

Expanded from @kennebec 's answer, but handles the edge cases his fails at better (Gist, with CoffeeScript):

  String.prototype.noExponents = function(explicitNum) {
    var data, leader, mag, multiplier, num, sign, str, z;
    if (explicitNum == null) {
      explicitNum = true;
    }

    /*
     * Remove scientific notation from a number
     *
     * After
     * http://stackoverflow.com/a/18719988/1877527
     */
    data = this.split(/[eE]/);
    if (data.length === 1) {
      return data[0];
    }
    z = "";
    sign = this.slice(0, 1) === "-" ? "-" : "";
    str = data[0].replace(".", "");
    mag = Number(data[1]) + 1;
    if (mag <= 0) {
      z = sign + "0.";
      while (!(mag >= 0)) {
        z += "0";
        ++mag;
      }
      num = z + str.replace(/^\-/, "");
      if (explicitNum) {
        return parseFloat(num);
      } else {
        return num;
      }
    }
    if (str.length <= mag) {
      mag -= str.length;
      while (!(mag <= 0)) {
        z += 0;
        --mag;
      }
      num = str + z;
      if (explicitNum) {
        return parseFloat(num);
      } else {
        return num;
      }
    } else {
      leader = parseFloat(data[0]);
      multiplier = Math.pow(10, parseInt(data[1]));
      return leader * multiplier;
    }
  };

  Number.prototype.noExponents = function() {
    var strVal;
    strVal = String(this);
    return strVal.noExponents(true);
  };