How to set request headers globally in jquery

jQuery is an open source JavaScript library written based on JavaScript. It is commonly used in website development and is mainly used to simplify the operation between HTML and JavaScript. When using Ajax to request data, you often need to set request header information so that the backend server can accurately handle the request. In jQuery, we can also easily set global request headers. This article will explain in detail how to set jQuery request headers globally.

1. Why set request headers

When sending an Ajax request, some request header information can allow the server to better understand the purpose of the request. For example, the Accept header tells the server the data types (MIME types) that the client can accept, the Content-Type header tells the server the data type requested, and the Authorization header sends user authentication information to the server when authentication is required.

So, when writing Ajax requests, it is very important to set the request header correctly, and it is also a basic requirement to comply with Web development specifications.

2. Set global request headers

In jQuery, you can set global Ajax request options, including ajax request header information, through the ajaxSetup() method. The ajaxSetup() method allows us to override global Ajax settings and set default values.

The method of setting request headers globally is as follows:

$.ajaxSetup({
    headers: {
        'X-CSRF-Token': $('meta[name="csrf-token"]').attr('content'),
        'Authorization': 'Bearer token'
    }
});

In the above code, we use the headers attribute to set two request headers: X-CSRF-Token and Authorization.

Among them, X-CSRF-Token is the token used for cross-site request forgery (CSRF). When using POST, PUT, DELETE and other requests, you need to add a CSRF token in the request header or request parameters to facilitate verification in the background to ensure the legitimacy of the request.

The Authorization header is used to send user authentication information to the server when authentication is required. Generally, user authentication information will be appended to the request header.

It should be noted that when setting the request header globally, you should pay attention to the timing and scope to ensure that it will not interfere with unnecessary requests or other requests. In addition, after changing the global settings, all subsequent requests will be affected. Therefore, you need to consider various possible situations when making global settings to ensure that the set information is reasonable and effective.

3. Set specific request headers

In addition to setting request headers globally, we can also set specific request headers as needed. When using jQuery's $.ajax() method, you can set the request headers through the headers parameter. It is an object that contains the request header attributes and values ​​that need to be set. For example:

$.ajax({
    url: 'index.html',
    headers: {
        'X-CSRF-Token': $('meta[name="csrf-token"]').attr('content'),
        'Authorization': 'Bearer token'
    },
    success: function(response){
        console.log(response);
    },
    error: function(){
        console.log('请求失败');
    }
});

In the above code, we set the headers object in the $.ajax() method to set the request headers. It contains the request header attributes and corresponding values ​​that need to be set.

It should be noted that when using specific request headers, you should pay attention to the impact that may affect subsequent requests.

4. Summary

In order to correctly handle Ajax requests, correctly setting the request header is an essential step. In jQuery, we can accomplish this by setting request headers globally and specific request headers.

To set request headers globally, use the ajaxSetup() method to set multiple request headers at one time. It will work on all Ajax requests. Globally set request headers should be used with caution.

Specific request headers are set through the headers parameter when using the $.ajax() method. Different request headers can be set in different Ajax requests.

Having mastered the way to set request headers globally and specific request headers, developers can use request headers more flexibly and efficiently in Ajax requests.

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