9/27/2023 0 Comments What is js nodeThere's no more code to run, so the global function is also popped off the stack. As there are no more statements to execute in the callback function, it is popped off as well. That is pushed to the call stack, "Second" is logged to the console, and the log function is popped off. Within the callback function, the log statement is encountered. The associated callback function is now executed on the call stack. At 3ms, JavaScript proceeds to line 7, pushes the log function onto the stack, "Third" is logged to the console, and the function is popped off the stack.Īt about 4ms, let's say that the file read task is completed in the thread pool. In the background, libuv starts to read the file contents on a separate thread. JavaScript pops off the readFile method from the call stack because its job is done as far as the execution of line 3 is concerned. Since readFile is an asynchronous operation, it is off-loaded to libuv. At 2ms, the readFile method is pushed onto the stack. At 1ms, "First" is logged in the console, and the function is popped off the stack. The global function is pushed onto the stack. The main thread of execution always starts in the global scope. In case the native mechanisms are not available or inadequate, it utilizes its thread pool to run the task, ensuring that the main thread is not blocked. Libuv then runs the task using native asynchronous mechanisms of the operating system. Whenever we execute an asynchronous method, libuv takes over the execution of the task. On the right side of the image, we have libuv, which is responsible for handling asynchronous methods. This is a straightforward implementation of the stack data structure, where the last item added is the first one to be removed. When a function returns, it is popped off the call stack. Whenever we declare variables or functions, memory is allocated on the heap, and whenever we execute code, functions are pushed into the call stack. The engine comprises a memory heap and a call stack. When we execute code, the V8 engine, located on the left side of the image, handles the execution of JavaScript code. Let’s conceptualize how code typically executes in the Node runtime.
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