git.r.bdr.sh - rbdr/dotfiles/blob

   1 'use strict';
   2
   3 var isPlainArray = require('../../is-plain-array')
   4   , toPosInt     = require('../../../number/to-pos-integer')
   5   , isObject     = require('../../../object/is-object')
   6
   7   , isArray = Array.isArray, concat = Array.prototype.concat
   8   , forEach = Array.prototype.forEach
   9
  10   , isSpreadable;
  11
  12 isSpreadable = function (value) {
  13         if (!value) return false;
  14         if (!isObject(value)) return false;
  15         if (value['@@isConcatSpreadable'] !== undefined) {
  16                 return Boolean(value['@@isConcatSpreadable']);
  17         }
  18         return isArray(value);
  19 };
  20
  21 module.exports = function (item/*, …items*/) {
  22         var result;
  23         if (!this || !isArray(this) || isPlainArray(this)) {
  24                 return concat.apply(this, arguments);
  25         }
  26         result = new this.constructor(this.length);
  27         forEach.call(this, function (val, i) { result[i] = val; });
  28         forEach.call(arguments, function (arg) {
  29                 var base;
  30                 if (isSpreadable(arg)) {
  31                         base = result.length;
  32                         result.length += toPosInt(arg.length);
  33                         forEach.call(arg, function (val, i) { result[base + i] = val; });
  34                         return;
  35                 }
  36                 result.push(arg);
  37         });
  38         return result;
  39 };