在Javascript中，我們可以通過prototype關(guān)鍵字為對(duì)象添加新的屬性或者是方法，下面是一個(gè)為Array對(duì)象添加二分法查找功能的方法： 代碼如下: Array.prototype.binarySearch = function(obj) { var value = 0; var left = 0; var right= this.length; while(left <= right) { var center = Math.floor((left+right)/2); if(this[center] == obj) { value = center; } if(obj < this[center]) { right = center - 1; } else { left = center + 1; } } alert(value); } //如下為測(cè)試代碼： function testArrayBinarySearch() { var array = new Array(); var key = 678; var number = 1000; for (i = 0; i < number; i++) { array.push(i); } array.binarySearch(key); } window.onload = function() { testArrayBinarySearch(); }
下面是國外的代碼 javascript二分法 //Copyright 2009 Nicholas C. Zakas. All rights reserved. //MIT-Licensed, see source file 代碼如下: function binarySearch(items, value){ var startIndex = 0, stopIndex = items.length - 1, middle = Math.floor((stopIndex + startIndex)/2); while(items[middle] != value && startIndex < stopIndex){ //adjust search area（調(diào)整查找范圍） if (value < items[middle]){ stopIndex = middle - 1; } else if (value > items[middle]){ startIndex = middle + 1; } //recalculate middle（重新計(jì)算中項(xiàng)索引） middle = Math.floor((stopIndex + startIndex)/2); } //make sure it's the right value（確保返回正確的值） return (items[middle] != value) ? -1 : middle; }
