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JSON object

2022-07-25 22:31:00 【Like the rising sun】

1. Preface

I have learned today JavaScript JSON, Want to learn well JavaScript JSON, You need to know first JSON What is it? ,JSON（JavaScript Object Notation） Is a kind of formatted text ,JavaScript Medium JSON object Used to process this kind of text .

2.JSON object

JSON The object is enclosed in curly braces {} Surround .

JSON Object with key / Value pair writing .

The key must be a string , Value must be valid JSON data type （ character string 、 Numbers 、 object 、 Array 、 Boor or null）.

Keys and values are separated by colons .

Each key / Value pairs are separated by commas .

1. Access object value

You can use point numbers （.） To access object values ：

var myJSON =  {
     "name":"xiaot", "sex":"male", "age":32 }

        var jsonName = myJSON.name;
        
        console.log(jsonName);

Words can be passed through square brackets （[]） To access object values ：

var myJSON =  {
     "name":"xiaot", "sex":"male", "age":32 }

        var jsonName = myJSON["name"];

        console.log(jsonName);

2. Traversing objects

Sure By using for-in Traverse object properties ：

<!DOCTYPE html>
<html>
<body>
<p> Traverse  JSON  All properties in the object .</p>

<p id="demo"></p>
<script> var myJSON = {
       "name": "xiaot", "sex": "male", "age": 32 } var x; for (x in myJSON) {
       document.getElementById("demo").innerHTML += x + "</br>"; } </script>

</body>
</html>

The running code is as follows ：

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3. nesting JSON object

nesting JSON Object refers to a JSON The value in the object can be another JSON object .

 myJSON = {
    
            "name": "xiaot",
            "age": 88,
            "cars": {
    
                "car1": "lamborghini",
                "car2": "Mercedes Benz",
                "car3": "Bugatti Veyron"
            }
        }

Nested JSON object ：

	x = myJSON.cars.car2;
	// perhaps 
    x = myJSON.cars["car2"];
	console.log(x);

You can make it clear from the console
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3. Summary

about AJAX For applications ,JSON Than XML Faster and easier to use , So mastering these knowledge points is beneficial without harm ！

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