Call function in java script once with closure

Question

I want call function once in java script and for implement this idea I write this code and I use closure

function initialize() {
  let called = 0;
  return function() {
    if (called > 0) {
      return
    } else {
      called++;
      console.log('view has been set!')
    }

  }
}

const start1 = initialize();
start1();
start1();
start1();

I call start1 function third time and when I run this code I get once this output "view has been set!" in console. But I notice I can call initialize function many times and create different start function for example

const start1 = initialize();
const start2 = initialize();
start1();
start2();

This time in output I have twice "view has been set!". How can I fix that. thanks.

written like this you will always get it one time. If you name the closure function and call it one time after the function declaration it will be called only one time. — Devolux, May 09 '21 at 08:43
Looks like it's already answered here: https://stackoverflow.com/questions/12713564/function-in-javascript-that-can-be-called-only-once — Ionuț Păduraru, May 09 '21 at 09:03

score 2 · Accepted Answer · answered May 09 '21 at 08:49

By keeping the structure of calling initialize, you need a closure which works without the first call of initialize.

Then you need a nested function to get the inner function for the working part.

const initialize = (() => {
  let called = 0;
  return () => () => {
    if (called <= 0) {
      called++;
      console.log('view has been set!');
    }
  };
})();


const start1 = initialize();
const start2 = initialize();
start1();
start2();

score 0 · Answer 2 · answered May 09 '21 at 08:50

0

When you call initialize function every times a new called variable is created which assigned to value 0.

answered May 09 '21 at 08:50

Orion

248
3
10

score 0 · Answer 3 · answered May 09 '21 at 09:31

I believe what you are looking for is a singleton. You can try this approach.

 
class initialize {
    constructor(){
        
     if(! initialize.instance){
       this._data = [];
      

       initialize.instance = this;
       console.log('view has been set!')
     }
  
     return initialize.instance;
    }
  
    dosmt=()=>{
        console.log("smt"    )
    }
 
  }
  
  const instance = new initialize();
  Object.freeze(instance);



  const start1 = new initialize() ;
  const start2 = new initialize();
  const start3 = new initialize();
start1.dosmt() 
start2.dosmt() 
start3.dosmt()

Call function in java script once with closure

3 Answers3