Have you ever had a thought of asking someone about how exactly Nodejs event loop works?
If yes, please go through the whole blog to know how Nodejs carriers the event loop as a driven mechanism.
NODEJS EVENT LOOP
Event-loop programming is a flow control in an application-defined by events. The basic principle of Nodejs’s event-driven loop is implementing a central mechanism. It hears for events and calls the callback function once an event is turned up. Nodejs is an event-loop that implements a run-time environment model to achieve non-blocking asynchronous behavior.
An event-loop which is run by Node thread goes active until a task gets complete. Then it activates the secondary event which signals the event-listener function to execute the task on time.
As soon as Nodejs begins to work, it initializes an event loop that processes the given input script(i.e)variable initiation and function declaration which makes asynchronous API calls and schedule timers, then begins processing the event loop.
- Web API
- Callback queue
In an execution process, If that particular function calls another function, then that function gets a call to the top of the stack. So the event loop process triggers a callback queue after the stack is empty. When our stacks have no function call then a process is pulling out from the callback queue and push it to stack back again.
Understand the Nodejs event loop with an example:
NO ASYNC CODE
console.log("first code"); console.log("second code"); console.log("third code");
In the above code, we are a simple console of three states such as first code, second code, and third code. They simply print the console in the same order as they are:
Now let’s understand the above code in a step by step manner:
- console.log(“first”) is executed.
- console.log(“first”) removed from the call stack.
- Now, console.log(“second”) is added to the call stack.
- console.log(“second”) is executed.
- After execution, console.log(“second”) removed from the call stack.
- Now the last line of the code, console.log(“third”) is added in the call stack.
- console.log(“third”) is executed.
- console.log(“third) is removed from the call stack.
This is how the event loop in Nodejs works and improves the performance of any Nodejs web applications.
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