aboutsummaryrefslogtreecommitdiff
path: root/node_modules/lodash/_createRound.js
blob: 88be5df396b61c2911732fea60d865cccf994b7a (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
var root = require('./_root'),
    toInteger = require('./toInteger'),
    toNumber = require('./toNumber'),
    toString = require('./toString');

/* Built-in method references for those with the same name as other `lodash` methods. */
var nativeIsFinite = root.isFinite,
    nativeMin = Math.min;

/**
 * Creates a function like `_.round`.
 *
 * @private
 * @param {string} methodName The name of the `Math` method to use when rounding.
 * @returns {Function} Returns the new round function.
 */
function createRound(methodName) {
  var func = Math[methodName];
  return function(number, precision) {
    number = toNumber(number);
    precision = precision == null ? 0 : nativeMin(toInteger(precision), 292);
    if (precision && nativeIsFinite(number)) {
      // Shift with exponential notation to avoid floating-point issues.
      // See [MDN](https://mdn.io/round#Examples) for more details.
      var pair = (toString(number) + 'e').split('e'),
          value = func(pair[0] + 'e' + (+pair[1] + precision));

      pair = (toString(value) + 'e').split('e');
      return +(pair[0] + 'e' + (+pair[1] - precision));
    }
    return func(number);
  };
}

module.exports = createRound;