using setTimeout in for loop

Question

I am trying write a function which print 5 wait to 1 sec and print number 4 wait for 2 secs and print number 3 wait for 3 secs and so on

I wrote this function :

for(let i=5;i>0;i--){
   setTimeout(()=>{
   let localTime = new Date().toLocaleString();
    console.log(`${i} - ${localTime}`)
  },5-i*1000);
}

And this prints:

'5 - 10/30/2019, 11:10:17 AM'
'4 - 10/30/2019, 11:10:17 AM'
'3 - 10/30/2019, 11:10:17 AM'
'2 - 10/30/2019, 11:10:17 AM'
'1 - 10/30/2019, 11:10:17 AM'

I wrote these set of statements :

console.log(new Date().toLocaleString());

 setTimeout(()=>{
  let localTime = new Date().toLocaleString();
    console.log(`${5} - ${localTime}`)
},1000)

setTimeout(()=>{
  let localTime = new Date().toLocaleString();
    console.log(`${4} - ${localTime}`)
},2*1000)

setTimeout(()=>{
  let localTime = new Date().toLocaleString();
    console.log(`${3} - ${localTime}`)
},3*1000)
setTimeout(()=>{
  let localTime = new Date().toLocaleString();
    console.log(`${2} - ${localTime}`)
},4*1000)
setTimeout(()=>{
  let localTime = new Date().toLocaleString();
    console.log(`${1} - ${localTime}`)
},5*1000)

And these print:

'10/30/2019, 11:13:45 AM'
'5 - 10/30/2019, 11:13:46 AM'
'4 - 10/30/2019, 11:13:47 AM'
'3 - 10/30/2019, 11:13:48 AM'
'2 - 10/30/2019, 11:13:49 AM'
'1 - 10/30/2019, 11:13:50 AM'

The second set of statements are increasing the time by 1 sec but the set time out in for loop is not doing.

How to achieve the functionality and where am I going wrong?

I think setInterval is a better approach for you: w3schools.com/jsref/met_win_setinterval.asp — David
– David, Commented Oct 30, 2019 at 16:22

epascarello · Accepted Answer · 2019-10-30 16:47:53Z

2

Order of operations

5 - 1 * 1000
5 - (1*1000)
5 - 1000
-995

It needs to have parenthesis

},(5-i) * 1000);

A better way without the for loop is just create a function and have the timer recursively call it until it is done.

function countDown (max) {
   function execute () {
     let localTime = new Date().toLocaleString();
     console.log(`${max} - ${localTime}`)
     max -= 1
     if (max>0) window.setTimeout(execute, 1000)
   }
   execute()
}

countDown(5);

edited Oct 30, 2019 at 16:47

answered Oct 30, 2019 at 16:24

epascarello

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1 Comment

epascarello Over a year ago

Guess downvoter thinks it should been closed and not answered. :)

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