JavaScript学习与实践(21)
JS中的数组对象,他用于使用一个变量名字存储一组值,
例子:这个例子是创建一个数组,并分配了数值,最后打印出其中的值,
<html> <body> <script type="text/javascript"> var mycars = new Array() mycars[0] = "Saab" mycars[1] = "Volvo" mycars[2] = "BMW" for (i=0;i<mycars.length;i++) { document.write(mycars[i] + "<br />") } </script> </body> </html>
下面是一个for...in,怎么用他来循环便利数组中的每个元素呢?
<html> <body> <script type="text/javascript"> var x var mycars = new Array() mycars[0] = "Saab" mycars[1] = "Volvo" mycars[2] = "BMW" for (x in mycars) { document.write(mycars[x] + "<br />") } </script> </body> </html>
下面是一个连接两个数组的方法concat()
<html> <body> <script type="text/javascript"> var arr = new Array(3) arr[0] = "Jani" arr[1] = "Tove" arr[2] = "Hege" var arr2 = new Array(3) arr2[0] = "John" arr2[1] = "Andy" arr2[2] = "Wendy" document.write(arr.concat(arr2)) </script> </body> </html>
下面是一个join()方法,他是把一个数组中所有的元素方到一个字符串中,,其中可以指定标点符号例子:
<html> <body> <script type="text/javascript"> var arr = new Array(3) arr[0] = "Jani" arr[1] = "Hege" arr[2] = "Stale" document.write(arr.join() + "<br />") document.write(arr.join(".")) </script> </body> </html>
下面一个是分类,区别的sort(),他用于字面的,或者是数字的下面有两个例子来加以区别:
<html> <body> <script type="text/javascript"> var arr = new Array(6) arr[0] = "Jani" arr[1] = "Hege" arr[2] = "Stale" arr[3] = "Kai Jim" arr[4] = "Borge" arr[5] = "Tove" document.write(arr + "<br />") document.write(arr.sort()) </script> </body> </html>
第二个
<html> <body> <script type="text/javascript"> function sortNumber(a, b) { return a - b } var arr = new Array(6) arr[0] = "10" arr[1] = "5" arr[2] = "40" arr[3] = "25" arr[4] = "1000" arr[5] = "1" document.write(arr + "<br />") document.write(arr.sort(sortNumber)) </script> </body> </html>
上面这个我还没有理解,希望大家,指导我一下,谢谢
Array Object Methods
FF: Firefox, N: Netscape, IE: Internet Explorer
Method | Description | FF | N | IE |
---|---|---|---|---|
concat() | Joins two or more arrays and returns the result | 1 | 4 | 4 |
join() | Puts all the elements of an array into a string. The elements are separated by a specified delimiter | 1 | 3 | 4 |
pop() | Removes and returns the last element of an array | 1 | 4 | 5.5 |
push() | Adds one or more elements to the end of an array and returns the new length | 1 | 4 | 5.5 |
reverse() | Reverses the order of the elements in an array | 1 | 3 | 4 |
shift() | Removes and returns the first element of an array | 1 | 4 | 5.5 |
slice() | Returns selected elements from an existing array | 1 | 4 | 4 |
sort() | Sorts the elements of an array | 1 | 3 | 4 |
splice() | Removes and adds new elements to an array | 1 | 4 | 5.5 |
toSource() | Represents the source code of an object | 1 | 4 | - |
toString() | Converts an array to a string and returns the result | 1 | 3 | 4 |
unshift() | Adds one or more elements to the beginning of an array and returns the new length | 1 | 4 | 6 |
valueOf() | Returns the primitive value of an Array object | 1 | 2 | 4 |
Array Object Properties
Property | Description | FF | N | IE |
---|---|---|---|---|
constructor | A reference to the function that created the object | 1 | 2 | 4 |
index | 1 | 3 | 4 | |
input | 1 | 3 | 4 | |
length | Sets or returns the number of elements in an array | 1 | 2 | 4 |
prototype | Allows you to add properties and methods to the object | 1 | 2 | 4 |