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85JS原生:数组4种去重方法
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85JS原生:数组4种去重方法
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1、新數(shù)組去重:重新構(gòu)建一個(gè)新數(shù)組,遍歷原數(shù)組的每一項(xiàng),如果該項(xiàng)在新數(shù)組的索引為-1,則把該項(xiàng)添加到新數(shù)組中。
**html 代碼**
```html:run
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>新數(shù)組去重</title>
</head>
<body>
<script>
var ary = [21, 32, 32, 4, 5, 61, 61, 21, 4, 5, 61];
var newAry=[];
for(var i=0; i<ary.length; i++){
if(newAry.indexOf(ary[i])===-1){
newAry[newAry.length]=ary[i];
}
}
document.write(newAry);
</script>
</body>
</html>
```
2、對(duì)象法數(shù)組去重:如果對(duì)象中沒有這一項(xiàng),給對(duì)象添加屬性名和屬性值,如果對(duì)象中已經(jīng)有了,說明是重復(fù)的,直接在數(shù)組中刪除這一項(xiàng);
**html 代碼**
```html:run
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>對(duì)象法數(shù)組去重</title>
</head>
<body>
<script>
var ary = [21, 32, 32, 4, 5, 61, 61, 21, 4, 5, 61,61];
var obj={};
for(var i=0; i<ary.length; i++){
var cur=ary[i];
if(obj[cur]===cur){//說明重復(fù)了
ary.splice(i,1);
i--;
}else{
obj[cur]=cur;
}
}
document.write(ary);
</script>
</body>
</html>
```
3、sort排序法去重:先用sort方法對(duì)數(shù)組進(jìn)行排序,然后拿前一項(xiàng)與后一項(xiàng)進(jìn)行比較,如果相等,則刪除前一項(xiàng),同時(shí)為了防止數(shù)組塌陷,下一次仍從該項(xiàng)開始比較。
**html 代碼**
```html:run
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>sort排序</title>
</head>
<body>
<script>
var ary = [21, 32, 32, 4, 5, 61, 61, 21, 4, 5, 61];
ary.sort(function (a, b) {
return a - b;
});
for (var i = 0; i < ary.length; i++) {
if (ary[i] === ary[i + 1]) {
ary.splice(i, 1);
i--;
}
}
document.write(ary);
</script>
</body>
</html>
```
4、雙循環(huán)去重:第一個(gè)循環(huán),依次取出數(shù)組的每一項(xiàng)A;第二個(gè)循環(huán),從數(shù)組的A項(xiàng)開始,依次與A項(xiàng)進(jìn)行比較,如果相等則刪除,同時(shí)為了防止數(shù)組塌陷,下一次仍從該項(xiàng)開始比較。
**html 代碼**
```html:run
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>雙循環(huán)去重</title>
</head>
<body>
<script>
var ary = [21, 32, 32, 4, 5, 61, 61, 21, 4, 5, 61];
for (var i = 0; i < ary.length; i++) {
var cur = ary[i];
for (var j = i + 1; j < ary.length; j++) {
if (cur === ary[j]) {
ary.splice(j, 1);
j--;
}
}
}
document.write(ary);
</script>
</body>
</html>
```
**html 代碼**
```html:run
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>新數(shù)組去重</title>
</head>
<body>
<script>
var ary = [21, 32, 32, 4, 5, 61, 61, 21, 4, 5, 61];
var newAry=[];
for(var i=0; i<ary.length; i++){
if(newAry.indexOf(ary[i])===-1){
newAry[newAry.length]=ary[i];
}
}
document.write(newAry);
</script>
</body>
</html>
```
2、對(duì)象法數(shù)組去重:如果對(duì)象中沒有這一項(xiàng),給對(duì)象添加屬性名和屬性值,如果對(duì)象中已經(jīng)有了,說明是重復(fù)的,直接在數(shù)組中刪除這一項(xiàng);
**html 代碼**
```html:run
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>對(duì)象法數(shù)組去重</title>
</head>
<body>
<script>
var ary = [21, 32, 32, 4, 5, 61, 61, 21, 4, 5, 61,61];
var obj={};
for(var i=0; i<ary.length; i++){
var cur=ary[i];
if(obj[cur]===cur){//說明重復(fù)了
ary.splice(i,1);
i--;
}else{
obj[cur]=cur;
}
}
document.write(ary);
</script>
</body>
</html>
```
3、sort排序法去重:先用sort方法對(duì)數(shù)組進(jìn)行排序,然后拿前一項(xiàng)與后一項(xiàng)進(jìn)行比較,如果相等,則刪除前一項(xiàng),同時(shí)為了防止數(shù)組塌陷,下一次仍從該項(xiàng)開始比較。
**html 代碼**
```html:run
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>sort排序</title>
</head>
<body>
<script>
var ary = [21, 32, 32, 4, 5, 61, 61, 21, 4, 5, 61];
ary.sort(function (a, b) {
return a - b;
});
for (var i = 0; i < ary.length; i++) {
if (ary[i] === ary[i + 1]) {
ary.splice(i, 1);
i--;
}
}
document.write(ary);
</script>
</body>
</html>
```
4、雙循環(huán)去重:第一個(gè)循環(huán),依次取出數(shù)組的每一項(xiàng)A;第二個(gè)循環(huán),從數(shù)組的A項(xiàng)開始,依次與A項(xiàng)進(jìn)行比較,如果相等則刪除,同時(shí)為了防止數(shù)組塌陷,下一次仍從該項(xiàng)開始比較。
**html 代碼**
```html:run
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>雙循環(huán)去重</title>
</head>
<body>
<script>
var ary = [21, 32, 32, 4, 5, 61, 61, 21, 4, 5, 61];
for (var i = 0; i < ary.length; i++) {
var cur = ary[i];
for (var j = i + 1; j < ary.length; j++) {
if (cur === ary[j]) {
ary.splice(j, 1);
j--;
}
}
}
document.write(ary);
</script>
</body>
</html>
```
轉(zhuǎn)載于:https://www.cnblogs.com/gushixianqiancheng/p/10967131.html
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