How to use promises in javascript ? Basic Promise in Javascript

Question

I am using redux. I want to perform a certain network call after updating store. I wrote promise for this as -

let promise=new Promise(function(resolve,reject){
updateStore() //separate method which updates the store.
}).then(()=>{    
 //Netowrk call
 //axios code
});

I am getting a syntax error here : Declaration or statement expected.

What should be the way of performing this activity?

If you don't mind moving it to an async function, you can use await, which will do the Promise magic, but without the additional syntax. Note that async/await isn't compatible with some older browsers. — tresf
– tresf, Commented Apr 29, 2022 at 5:21

Wayne Smith · Accepted Answer · 2022-04-29 05:16:40Z

1

You Can but not sure why you would want to use promise here? What are we waiting on?

function updateStore() {
   console.log("updating");
}

let promise=new Promise(function(resolve,reject){
  console.log('update')
  resolve( updateStore() ) //separate method which updates the store.
}).then(()=>{
  console.log('now network')    
 //Netowrk call
 //axios code
});

Using promise

Might be better served just to use a function.

function update_store(callback) {
   console.log("update store");
   callback(); /* or setTimeout( callback ); */
}

function now_network() {
   console.log("update network");
}

update_store(now_network);

Using callback

edited Apr 29, 2022 at 5:16

answered Apr 29, 2022 at 4:34

Wayne Smith

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2 Comments

C Sharper Over a year ago

network call uses updated store values..thats why we want to wait till store gets updated.

tresf Over a year ago

Most network calls have built-in promise-type handlers, so if the updateStore() function can be refactored, it might be as simple as updateStore().then(...) rather than handing it synchronously, then wrapping it asynchronously.

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