web 开发之js---js 中的数组操作
js數(shù)組元素的添加和刪除一直比較迷惑,今天終于找到詳細(xì)說(shuō)明的資料了,先給個(gè)我測(cè)試的代碼^-^
var arr = new Array();
arr[0] = "aaa";
arr[1] = "bbb";
arr[2] = "ccc";
//alert(arr.length);//3
arr.pop();
//alert(arr.length);//2
//alert(arr[arr.length-1]);//bbb
arr.pop();
//alert(arr[arr.length-1]);//aaa
//alert(arr.length);//1
var arr2 = new Array();
//alert(arr2.length);//0
arr2[0] = "aaa";
arr2[1] = "bbb";
//alert(arr2.length);//2
arr2.pop();
//alert(arr2.length);//1
arr2 = arr2.slice(0,arr2.length-1);?
//alert(arr2.length);//0
arr2[0] = "aaa";
arr2[1] = "bbb";
arr2[2] = "ccc";
arr2 = arr2.slice(0,1);?
alert(arr2.length);//1
alert(arr2[0]);//aaa
alert(arr2[1]);//undefined
?
shift:刪除原數(shù)組第一項(xiàng),并返回刪除元素的值;如果數(shù)組為空則返回undefined?
var a = [1,2,3,4,5];?
var b = a.shift(); //a:[2,3,4,5]?? b:1?
unshift:將參數(shù)添加到原數(shù)組開(kāi)頭,并返回?cái)?shù)組的長(zhǎng)度?
var a = [1,2,3,4,5];?
var b = a.unshift(-2,-1); //a:[-2,-1,1,2,3,4,5]?? b:7?
注:在IE6.0下測(cè)試返回值總為undefined,FF2.0下測(cè)試返回值為7,所以這個(gè)方法的返回值不可靠,需要用返回值時(shí)可用splice代替本方法來(lái)使用。?
pop:刪除原數(shù)組最后一項(xiàng),并返回刪除元素的值;如果數(shù)組為空則返回undefined?
var a = [1,2,3,4,5];?
var b = a.pop(); //a:[1,2,3,4]?? b:5 //不用返回的話直接調(diào)用就可以了
push:將參數(shù)添加到原數(shù)組末尾,并返回?cái)?shù)組的長(zhǎng)度?
var a = [1,2,3,4,5];?
var b = a.push(6,7); //a:[1,2,3,4,5,6,7]?? b:7?
concat:返回一個(gè)新數(shù)組,是將參數(shù)添加到原數(shù)組中構(gòu)成的?
var a = [1,2,3,4,5];?
var b = a.concat(6,7); //a:[1,2,3,4,5]?? b:[1,2,3,4,5,6,7]?
splice(start,deleteCount,val1,val2,...):從start位置開(kāi)始刪除deleteCount項(xiàng),并從該位置起插入val1,val2,...?
var a = [1,2,3,4,5];?
var b = a.splice(2,2,7,8,9); //a:[1,2,7,8,9,5]?? b:[3,4]?
var b = a.splice(0,1); //同shift?
a.splice(0,0,-2,-1); var b = a.length; //同unshift?
var b = a.splice(a.length-1,1); //同pop?
a.splice(a.length,0,6,7); var b = a.length; //同push?
reverse:將數(shù)組反序?
var a = [1,2,3,4,5];?
var b = a.reverse(); //a:[5,4,3,2,1]?? b:[5,4,3,2,1]?
sort(orderfunction):按指定的參數(shù)對(duì)數(shù)組進(jìn)行排序?
var a = [1,2,3,4,5];?
var b = a.sort(); //a:[1,2,3,4,5]?? b:[1,2,3,4,5]?
slice(start,end):返回從原數(shù)組中指定開(kāi)始下標(biāo)到結(jié)束下標(biāo)之間的項(xiàng)組成的新數(shù)組?
var a = [1,2,3,4,5];?
var b = a.slice(2,5); //a:[1,2,3,4,5]?? b:[3,4,5]?
join(separator):將數(shù)組的元素組起一個(gè)字符串,以separator為分隔符,省略的話則用默認(rèn)用逗號(hào)為分隔符?
var a = [1,2,3,4,5];?
var b = a.join("|"); //a:[1,2,3,4,5]?? b:"1|2|3|4|5"
再給個(gè)利用數(shù)組模擬javaStringBuffer處理字符串的方法:
/**
* 字符串處理函數(shù)
*/
function StringBuffer()
{
var arr = new Array;
this.append = function(str)
{
??? arr[arr.length] = str;?
};
this.toString = function()
{
??? return arr.join("");?//把a(bǔ)ppend進(jìn)來(lái)的數(shù)組ping成一個(gè)字符串
};
}
今天在應(yīng)用中突然發(fā)現(xiàn)join是一種把數(shù)組轉(zhuǎn)換成字符串的好方法,故封裝成對(duì)象使用了:
/**
* 把數(shù)組轉(zhuǎn)換成特定符號(hào)分割的字符串
*/
function arrayToString(arr,separator)
{
if(!separator) separator = "";//separator為null則默認(rèn)為空
??? return arr.join(separator);?
}
/**
* 查找數(shù)組包含的字符串
*/
function arrayFindString(arr,string)
{
var str = arr.join("");?
??? return str.indexOf(string);?
}
http://www.cnblogs.com/yuzhongwusan/archive/2008/12/15/1355378.html
http://www.cnblogs.com/qiantuwuliang/archive/2011/01/08/1930499.html 數(shù)組添加刪除操作實(shí)例
轉(zhuǎn)載于:https://www.cnblogs.com/pengkunfan/p/4040371.html
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