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javascript当中concat，join,slice用法
1.3（concat，join,slice）
马克- to-win：马克 java社区：防盗版实名手机尾号： 73203。
<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() + "<br>");
//与无参join()方法等同
var arrconcat=arr.concat(a, b);
document.write("arr.concat(a,b) is " + arrconcat + "<br>");
/*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() + "<br>");
//无参join()方法默认是用逗号连接
document.write("arr.join(' & ') is " + arr.join(' & ') + "<br>");
/* Array.reverse() (Method)
Reverse the order of array elements.
Property/method value type: Array object
*/
document.write("arr.reverse() is " + arr.reverse() + "<br>");
/*Array.sort() (Method)
Sort the elements in an array.
Property/method value type: Array object
JavaScript syntax: - myArray.sort()
*/
document.write("arr.sort() is " + arr.sort() + "<br>");
//如果调用该方法时没有参数，将按字母顺序进行排序
document.write("a is " + a + "<br>");
/* returned value type: Array object
JavaScript syntax: - myArray.slice(aRange)
a bit like substring, but substring is applicable to String, but slice is applicable to array.
allegedly,it includes former,exclude latter，一薄片面包:a slice of bread*/
var slicedArr = a.slice(0, 2);
document.write("a.slice(0,2) is " + slicedArr + "<br>");
//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
document.write("a.slice(1) is " + a.slice(1) + "<br>");
</script>
</head>
<body>
</body>
</html>
输出结果：
typeof arr is objectarr.length is 1a.length is 4arr.toString() is java,intel,microsoft
arr.concat(a,b) is java,intel,microsoft,2,6,5,a,12,14
arr.join() is java,intel,microsoft
arr.join(' & ') is java & intel & microsoft
arr.reverse() is microsoft,intel,java
arr.sort() is intel,java,microsoft
a is 2,6,5,a
a.slice(0,2) is 2,6
a.slice(1) is 6,5,a
例 1.4
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<HTML>
<head>
<meta http-equiv="content-type" content="text/html; charset=utf-8"/>
<script type="text/javascript">
function sortNumber(a, b)
{
document.write(a + b);
}
function sortq(sortNumberqqq)
{
document.write("here");
sortNumberqqq(1, 2);
return 6;
}
/* 马克-to-win：note that it will report error if we write the following statement as document.write("test "+sortq(sortNumberqixy));
note that here sortNumber is a function pointer.
*/
document.write("test " + sortq(sortNumber));
</script>
</HEAD>
<BODY>
</BODY>
</HTML>
输出结果：
here3test 6
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