json数组，json数组详解-励北网

json数组，json数组详解

简单说，所谓对象，就是一种无序的数据集合，由若干个“键值对”（key-value）构成。

一、数组作为JSON对象

[ "Ford", "BMW", "Fiat" ]

在JSON中的数组，几乎和在JavaScript中数组相同。

在JSON中，数组的值必须是字符串，数字、对象、数组、布尔值或空.

JavaScript中，数组的值可以是以上所有，再加上其他任何有效的JavaScript表达式，包括函数、日期、和undefined。

二、JSON对象中的数组

数组可以是对象属性的值:

{"name":"John","age":30,"cars":[ "Ford", "BMW", "Fiat" ]}

1. 访问数组的值

使用索引号访问数组值:

x = myObj.cars[0];

完整代码：

<!DOCTYPE html><html lang="en"> <head> <meta charset="UTF-8"> <title>项目</title> </head> <body style="background-color: aqua;"> <p id="demo"></p> <script> myObj = { "name": "John", "age": 30, "cars": ["Ford", "BMW", "Fiat"] } x = myObj.cars[0]; document.getElementById("demo")[xss_clean] = x;</script> </body> </html>

json数组，json数组详解

2. 遍历数组

你可以使用for-in循环遍历数组:

for (i in myObj.cars) { x += myObj.cars[i];}

或者可以使用for循环:

for (i = 0; i < myObj.cars.length; i++) { x += myObj.cars[i];}

json数组，json数组详解

三、JSON对象中的嵌套数组

数组值也可以是另一个数组，甚至另一个JSON对象:

myObj = { "name":"John", "age":30, "cars": [ { "name":"Ford", "models":[ "Fiesta", "Focus", "Mustang" ] }, { "name":"BMW", "models":[ "320", "X3", "X5" ] }, { "name":"Fiat", "models":[ "500", "Panda" ] } ] }

访问数组内部的数组, 使用for-in loop循环:

<!DOCTYPE html><html lang="en"><head> <meta charset="UTF-8"> <title>项目</title></head><body style="background-color: aqua;"> <p>Looping through arrays inside arrays.</p> <p id="demo"></p> <script> var myObj, i, j, x = ""; myObj = { "name":"John", "age":30, "cars": [ { "name":"Ford", "models":[ "Fiesta", "Focus", "Mustang" ] }, { "name":"BMW", "models":[ "320", "X3", "X5" ] }, { "name":"Fiat", "models":[ "500", "Panda" ] } ] }/*访问数组内部的数组, 使用for-in loop循环*/ for (i in myObj.cars) { x += "<h1>" + myObj.cars[i].name + "</h1>"; for (j in myObj.cars[i].models) { x += myObj.cars[i].models[j] + "<br>"; } } document.getElementById("demo")[xss_clean] = x;</script></body></html>

json数组，json数组详解

1. 修改数组值

使用索引号修改数组:

myObj.cars[1] = "Mercedes";

完整代码：

<!DOCTYPE html><html lang="en"><head> <meta charset="UTF-8"> <title>项目</title></head><body> <p id="demo"></p> <script> var myObj, i, x = ""; myObj = { "name":"John", "age":30, "cars":[ "Ford", "BMW", "Fiat" ] }; myObj.cars[1] = "Mercedes"; for (i in myObj.cars) { x += myObj.cars[i] + "<br>"; } document.getElementById("demo")[xss_clean] = x;</script> </body></html>

json数组，json数组详解