Details about how the server code will generate JSON-format metadata

Source: Internet
Author: User

You can use JavaScript Object NotationJSON to group and cache metadata, and use JavaScript Functions to access metadata to verify user input. In this article, you will learn how to cache metadata on the client with the help of the server code. The server code will provide JSON-formatted string metadata.

Every application is developed to solve problems in a certain field. Each field has its own set of rules and specifications that constrain data. When applications apply these constraints to data, the constraints are verified. All applications need to verify the data entered by the user.

Currently, applications generally use a combination of if-else statements to verify data. These statements contain verification data that is hard-coded by the developer or placed through the server code. Generally, developers use server-side code to avoid minor data changes that may lead to JavaServer PageJSP.

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When JavaScript contains scattered metadata, you cannot control how much data is evaluated and how much data is passed to the client. All server code snippets will be evaluated and sent to the server. However, when using JSON to cache data, you can completely control the amount of metadata sent to the client, because the server code will generate JSON-format metadata. This helps only send metadata to the client corresponding to the user who sees or inputs the data.

You can also use JSON to cache user input data. After the program caches data, it will erase the data field instead of refreshing the screen, which is similar to Ajax. In this way, you can enter another group of data for the same attribute. Let's explore how to use JSON to cache metadata.

JSON is called JavaScript Object Notation), which represents a JavaScript Object in a specific string format. If a string with such a form is assigned to any JavaScript variable, the variable then references an object constructed by a string specified to the variable.

For example, assume that a policy object has the following attributes: the Plan Name Describes the duration. You can use the following JSON string to represent the policy object: {"Plane ": {"Full Life Cover"}, "Description": {"The best life insurance plan"}, "Term": {"20 years "}}

If this string is assigned to any JSON format, the variable accepts data in units of this object. To access data, provide the path of the attribute to be accessed. In this example, assign the above string to a variable named policy: var policy = {"Plane": {"Full Life Cover"}, "Description ": {"The best life insurance plan"}, "Term": {"20 years"} paste this string INTO The TITLE section of The HTML page, and then write The following alert: alert (policy. plan) If you view this page in any browser that supports JavaScript, you will see an alert that displays the policy Plan.

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