Small snippets to hack double values in JavaScript

double-to-buffer.js

/**
 * Copyright (c) 2016, Robert Eisele ([email protected])
 * Dual licensed under the MIT or GPL Version 2 licenses.
 **/
// Converts a JavaScript double number to a node Buffer
var DoubleToBuffer = (function() {

  var FLOAT = new Float64Array(1)

  return function(x) {
    FLOAT[0] = x;

    var buffer = new Buffer(FLOAT.buffer.byteLength);
    var bytes = new Uint8Array(FLOAT.buffer);
    for (var i = 0; i < buffer.length; i++) {
        buffer[i] = bytes[i];
    }
    return buffer;
  };

})();

extract-exponent.js

/**
 * Copyright (c) 2016, Robert Eisele ([email protected])
 * Dual licensed under the MIT or GPL Version 2 licenses.
 **/
// Extracts the exponent of a double value x
var getExponent = (function() {

  var FLOAT = new Float64Array(1)
  var INT = new Uint32Array(FLOAT.buffer)
  var MIN_DENORM = Math.pow(2, -1023)

  return function(x) {
    FLOAT[0] = x;
    INT[0] = 0;
    INT[1] &= ~((1 << 20) - 1);
    return FLOAT[0] || MIN_DENORM;
  };

})();