js_content
The `js_content` directive allows execution of JavaScript code in response to HTTP requests, enabling dynamic content generation in NGINX.
Description
The js_content directive is part of the NGINX JavaScript module, allowing users to specify JavaScript code to be executed when handling an HTTP request in specific contexts such as location, if in location, and limit_except. This directive takes a single argument, which is the name of the JavaScript function to be called. The specified JavaScript function must be written in NJS (a subset of JavaScript compatible with ECMAScript 5.1) and is expected to manage the response using the ngx_http_request_t object. This allows developers to create complex logic on how requests are processed, including dynamic content generation, interacting with backend services, and modifying response headers.
When a request matches the location block that includes the js_content directive, NGINX calls the specified JavaScript function. This function can handle request parameters, cookies, and other HTTP attributes, allowing for a customizable response based on the request's content. Additionally, developers can interact with various NGINX features, such as setting response status codes or redirecting requests. This enhances the flexibility and power of NGINX as a web server or reverse proxy for applications.
Config Example
location /dynamic {
js_content my_js_function;
}Ensure that the specified JavaScript function is correctly defined and available in the script context.
Avoid using if directives unnecessarily, as they can create complex evaluation contexts that lead to unexpected behavior.
Be aware of asynchronous context; JavaScript functions in NGINX may need to handle asynchronous operations carefully.