javascript当中concat，join,slice用法

最新推荐文章于 2025-06-17 16:11:31 发布

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该博客主要通过示例介绍了JavaScript中数组的相关操作。定义了多个数组，展示了数组元素的赋值，重点讲解了concat、join等方法的使用。concat方法用于拼接数组，join方法可将数组元素连接成字符串，还提及了reverse和sort等方法。

例 1.3（concat，join,slice）
<html>
<head>
 <meta http-equiv="content-type" content="text/html; charset=utf-8"/>
 <Script>
 /* 马克-to-win：qixy: Array is a dynamic array.
 - myArray = new Array(aLength)
 - myArray = new Array(anItem1, anItem2, anItem3, ...)
 */
 var arr = new Array(1);//arr.length is 1,但是里面的东西是undefined，所以这样写[undefined]
/*虽然arr是个object，但是里面的东西是undefined*/
 document.write("typeof arr is "+typeof(arr));
 var a = new Array(2, 6, 5, "a");
 document.write("arr.length is "+arr.length+"a.length is "+a.length);
 var b = new Array(12, 14);
 arr[0] = "java";
 arr[1] = "intel";
 arr[2] = "microsoft";
 /* Property/method value type: Array object
 JavaScript syntax: - myArray.concat(someValues, ...)
 The result of this method is a new array consisting of the original array, plus the concatenation.
 The values that are passed to the method are added to the end of the array.
 If arrays are passed, they are flattened and their individual elements added.
 The method returns an array consisting of the original Array plus the concatenated values.
 If Array1 contains "AAA", "BBB", "CCC" and Array2 contains "000", "111", "222", then the method
 call Array1.concat(Array2) will return an array with all the elements in a single collection. The
 original arrays will be untouched.
 */
 document.write("arr.toString() is " + arr.toString() + " ");
 //与无参join()方法等同
 var arrconcat=arr.concat(a, b);
 document.write("arr.concat(a,b) is " + arrconcat + " ");
 /*Array.join() (Method)
 Concatenate array elements to make a string.
 Property/method value type: String primitive
 JavaScript syntax: - myArray.join(aSeparator)
 Argument list: aSeparator A string to place between array elements as the array is concatenated to form a string.
 //无参join()方法默认是用逗号连接
 */
 document.write("arr.join() is " + arr.join() + " ");
 //无参join()方法默认是用逗号连接
 document.write("arr.join(' & ') is " + arr.join(' & ') + " ");
 /* Array.reverse() (Method)
 Reverse the order of array elements.
 Property/method value type: Array object
 */
 document.write("arr.reverse() is " + arr.reverse() + " ");
 /*Array.sort() (Method)
 Sort the elements in an array.
 Property/method value type: Array object
 JavaScript syntax: - myArray.sort()
 */