How Can I Prevent JavaScript from Converting Large Integers to Scientific Notation?

Preventing Scientific Notation for Large Integers in JavaScript

Dealing with large integers in JavaScript can be tricky, as the language tends to convert them to scientific notation when used in a string context for numbers with more than 21 digits. This can be problematic, especially when printing integers as part of a URL. Fortunately, there are ways to prevent this conversion and maintain the full numerical value.

Native JavaScript Methods

JavaScript's Number.toFixed method can be used to format numbers to a specified decimal precision. However, it has a limitation: it switches to scientific notation for numbers greater than or equal to 1e21, and its maximum precision is 20.

Custom Implementation

For more flexibility, you can create your own function, such as the 'toFixed' function shown below:

function toFixed(x) {
  // Handle small values
  if (Math.abs(x) < 1.0) {
    var e = parseInt(x.toString().split('e-')[1]);
    if (e) {
        x *= Math.pow(10,e-1);
        x = '0.' + (new Array(e)).join('0') + x.toString().substring(2);
    }
  } 
  // Handle large values
  else {
    var e = parseInt(x.toString().split('+')[1]);
    if (e > 20) {
        e -= 20;
        x /= Math.pow(10,e);
        x += (new Array(e+1)).join('0');
    }
  }
  return x;
}

Beyond JavaScript

For complex scenarios involving large integers, consider using a BigInt library such as BigNumber, Leemon's BigInt, or BigInteger. The latest JavaScript version also introduces native BigInt support. To use it, simply convert the integer to a BigInt object using BigInt(n) and then call toString().

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