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Common methods of js array operation

高洛峰
Release: 2017-02-06 10:18:22
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Traversal is used more when processing JSON arrays in jquery, but adding and removing them does not seem to be too much.

I tried json[i].remove() and json.remove(i) today but it didn’t work. It seems that the JSON data appears in the form of an array in the DOM object of the web page. I checked the relevant JS It's really fun to try out the array operations.

record it.

1. Creation of arrays

var arrayObj = new Array(); //创建一个数组
var arrayObj = new Array([size]); //创建一个数组并指定长度,注意不是上限,是长度
var arrayObj = new Array([element0[, element1[, ...[, elementN]]]]); //创建一个数组并赋值
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It should be noted that although the second method creates an array with a specified length, in fact the array is variable length in all cases, that is to say Even if a length of 5 is specified, elements can still be stored outside the specified length. Note: the length will change accordingly.

2. Access to array elements

var testGetArrValue=arrayObj[1]; //获取数组的元素值
arrayObj[1]= "这是新值"; //给数组元素赋予新的值
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3. Addition of array elements

arrayObj. push([item1 [item2 [. . . [itemN ]]]]);// 将一个或多个新元素添加到数组结尾,并返回数组新长度
arrayObj.unshift([item1 [item2 [. . . [itemN ]]]]);// 将一个或多个新元素添加到数组开始,数组中的元素自动后移,返回数组新长度
arrayObj.splice(insertPos,0,[item1[, item2[, . . . [,itemN]]]]);//将一个或多个新元素插入到数组的指定位置,插入位置的元素自动后移,返回""。
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4. Deletion of array elements

arrayObj.pop(); //移除最后一个元素并返回该元素值
arrayObj.shift(); //移除最前一个元素并返回该元素值,数组中元素自动前移
arrayObj.splice(deletePos,deleteCount); //删除从指定位置deletePos开始的指定数量deleteCount的元素,数组形式返回所移除的元素
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5. Interception and merging

arrayObj.slice(start, [end]); //以数组的形式返回数组的一部分,注意不包括 end 对应的元素,如果省略 end 将复制 start 之后的所有元素
arrayObj.concat([item1[, item2[, . . . [,itemN]]]]); //将多个数组(也可以是字符串,或者是数组和字符串的混合)连接为一个数组,返回连接好的新的数组
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6. Copy of array

arrayObj.slice(0); //返回数组的拷贝数组,注意是一个新的数组,不是指向
arrayObj.concat(); //返回数组的拷贝数组,注意是一个新的数组,不是指向
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7. Sorting of array elements

arrayObj.reverse(); //反转元素(最前的排到最后、最后的排到最前),返回数组地址
arrayObj.sort(); //对数组元素排序,返回数组地址
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8. Stringization of array elements

arrayObj.join(separator); //返回字符串,这个字符串将数组的每一个元素值连接在一起,中间用 separator 隔开。
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toLocaleString, toString, valueOf: can be regarded as special usages of join, not commonly used

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