core-js/internals/string-trim.js

var requireObjectCoercible = require('../internals/require-object-coercible');
var whitespaces = require('../internals/whitespaces');

var whitespace = '[' + whitespaces + ']';
var ltrim = RegExp('^' + whitespace + whitespace + '*');
var rtrim = RegExp(whitespace + whitespace + '*$');

// `String.prototype.{ trim, trimStart, trimEnd, trimLeft, trimRight }` methods implementation
var createMethod = function (TYPE) {
  return function ($this) {
    var string = String(requireObjectCoercible($this));
    if (TYPE & 1) string = string.replace(ltrim, '');
    if (TYPE & 2) string = string.replace(rtrim, '');
    return string;
  };
};

module.exports = {
  // `String.prototype.{ trimLeft, trimStart }` methods
  // https://tc39.github.io/ecma262/#sec-string.prototype.trimstart
  start: createMethod(1),
  // `String.prototype.{ trimRight, trimEnd }` methods
  // https://tc39.github.io/ecma262/#sec-string.prototype.trimend
  end: createMethod(2),
  // `String.prototype.trim` method
  // https://tc39.github.io/ecma262/#sec-string.prototype.trim
  trim: createMethod(3)
};