core-js/modules/es.string.from-code-point.js

Standard library

var toAbsoluteIndex = require('../internals/to-absolute-index');
var fromCharCode = String.fromCharCode;
var nativeFromCodePoint = String.fromCodePoint;

// length should be 1, old FF problem
var INCORRECT_LENGTH = !!nativeFromCodePoint && nativeFromCodePoint.length != 1;

// `String.fromCodePoint` method
// https://tc39.github.io/ecma262/#sec-string.fromcodepoint
require('../internals/export')({ target: 'String', stat: true, forced: INCORRECT_LENGTH }, {
  fromCodePoint: function fromCodePoint(x) { // eslint-disable-line no-unused-vars
    var elements = [];
    var length = arguments.length;
    var i = 0;
    var code;
    while (length > i) {
      code = +arguments[i++];
      if (toAbsoluteIndex(code, 0x10ffff) !== code) throw RangeError(code + ' is not a valid code point');
      elements.push(code < 0x10000
        ? fromCharCode(code)
        : fromCharCode(((code -= 0x10000) >> 10) + 0xd800, code % 0x400 + 0xdc00)
      );
    } return elements.join('');
  }
});