js关于数组和对象基础

数组的显示

var arr1 = [[1,4,3],[4,6,6],[7,20,9]]

$.each(arr1,function(i,item){

alert(arr1[key[0])

})

//结果是1,4,7

对象的显示

var arr1= {"draw":1,"num1":[1,4,3],"num2":[4,6,6],"num3":[7,20,9]}

$.each(arr1,function(key,value){

alert(arr1[key[0]);

})

//结果是undefined, 1,4,7

var test =

[{"question":"the sky is blue",

 "answer":true

}

{

  "question":" the earth is flat",

 "answer":false

}

{

"question":"a cat is a dog",

"answer":false

}

]

alert(test)

alert(test[1].question)

alert(test[1].answer)

结果：[{object,object},[object,object],[object,object]}],以键值对体现

the earth is flat；

false

方法一：

var box ='[{"name:"a","age"：1}，{“”name“：“”b”,"age”:2}]'

alert(box);   //结果是[{"name:"a","age"：1}，{“”name“：“”b”,"age”:2}

var json = eval(box);

alert(json)  //结果：{object,object},[object,object],[object,object],

方法二：

var box = '[{"name" : "a","age" : 1},{"name" : "b","age" : 2}]'; //特别注意，键要用双引号
        alert(box);     //结果是[{"name:"a","age"：1}，{“”name“：“”b”,"age”:2}
        var json = JSON.parse(box); //不是双引号，会报错
        alert(json);    //结果：{object,object},[object,object],[object,object],

  var box = '[{"name" : "a","age" : 1},{"name" : "b","age" : 2}]';
        var json = JSON.parse(box, function (key, value) {
            if (key == 'name') {
                return 'Mr. ' + value;
            } else {
                return value;
            }
        });
        alert(json[1].name);   //结果是 Mr.b

    var test =

 var test =
            {
                "question": "the sky is blue",
                "answer": true,
                "alala":"the earth is flat"
            }
           
            
        alert(test.question)     //结果是 the sky is blue