| // 22.1.3.3 Array.prototype.copyWithin(target, start, end = this.length) |
| 'use strict'; |
| var toObject = require('./_to-object') |
| , toIndex = require('./_to-index') |
| , toLength = require('./_to-length'); |
| |
| module.exports = [].copyWithin || function copyWithin(target/*= 0*/, start/*= 0, end = @length*/){ |
| var O = toObject(this) |
| , len = toLength(O.length) |
| , to = toIndex(target, len) |
| , from = toIndex(start, len) |
| , end = arguments.length > 2 ? arguments[2] : undefined |
| , count = Math.min((end === undefined ? len : toIndex(end, len)) - from, len - to) |
| , inc = 1; |
| if(from < to && to < from + count){ |
| inc = -1; |
| from += count - 1; |
| to += count - 1; |
| } |
| while(count-- > 0){ |
| if(from in O)O[to] = O[from]; |
| else delete O[to]; |
| to += inc; |
| from += inc; |
| } return O; |
| }; |