CODEWITHSUNDEEP
javascriptnode.jsasynchronoussynchronous
Ali Beyit
Ali Beyit

Reputation: 414

Can I pause the execution of function until some value has been received in node?

Is there a way to hang/pause the function in the middle of its execution and then continue after few things are handled(input from the user received through socket.io) in node js? I know this is bad practice and need to use promises, async/await etc. However, according to the functionality of my program, I need to handle it this way.

My original question where I shared my code is here: Node application interactively get user input from react front end by pausing the current execution

Upvotes: 0

Views: 948

Answers (4)

Maheer Ali
Maheer Ali

Reputation: 36574

You can do that with async,await and Promise.

function func1(){
  console.log("function 1 is finished")
}
function func2(){
  console.log("function 2 is finished")
}

const thingsHandled = new Promise((res,rej) => {
    func1();
    func2();
    console.log("Every function is done")
    res();
})
   
async function main(){
    await thingsHandled;
    console.log("function is continued");
}
main();

Upvotes: 0

vicatcu
vicatcu

Reputation: 5837

... "pause the function in the middle of its execution" is unlikely to really be describing what you want to have happen. I assume you have some asynchronous code running that is responsible for getting your program to a point where "a few things are handled" ... so you code looks something like

  var a_few_things_have_been_handled = false;
  handle_a_few_things(); 
  // which returns immediately but has a side effect of 
  // effectively setting a_few_things_have_been_handled to true

  while(!a_few_things_have_been_handled) {
    // do nothing just wait...
    // actually you want to yield to asynchronous threads
    // but you can't do it like this
  }

  the_rest_of_your_program();

Unfortunately that's not how the language works... you have to restructure your program flow to be explicit about sequential program flow using Promises or similar asynchronous flow control constructs.

Upvotes: 1

Faisal Ahmed
Faisal Ahmed

Reputation: 390

you can do it using async/await feature in javascript. rewrite any callback-based function to use Promises, then await their resolution.

Upvotes: 0

Tom HANAX
Tom HANAX

Reputation: 432

You can wrap "second block" of your function in setTimeout() call, like this:

function f()
{
  statement1;
  setTimeout(() => {
    statement2;
  }, 1000);
}

Upvotes: 0

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