How to assign a value to a variable after each interval?

Question

I would like to run a script that repeats 100 times.

With each repetition it should be in order

Take the names from an array or list and pass them to my variable. How can I do this ?

I created this as an example and think about how I can install a function there. I've read and tried a few things. But somehow I'm not ready yet

var TestNames = ["test1", "test2", "test3", "test4", "test5"]
var n = TestNames[0]
interval = setInterval(function() {
  var Username = n;
  console.log(Username);
  // here is some code                           
}, 2000);
setTimeout(function() {
  clearInterval(interval)
}, 10000);

What is the logic to pick a name in each iteration? Is it random or by order? Does [`var Username = TestNames.shift();`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/shift) suffice? What happens when all names are iterated over? — Lain, Jan 17 '23 at 09:25

Lain · Answer 1 · 2023-01-17T11:34:24.177

Aassuming the setTimeout is calculcated by the amount of names (10000/2000), you can omit it entirely.

const TestNames = ["test1", "test2", "test3", "test4", "test5"];

//REM: https://developer.mozilla.org/en-US/docs/Web/API/setInterval
//REM: Passing a copy of TestNames to not alter the original
const interval = setInterval(function(listOfNames){ 
  if(listOfNames.length){
    //REM: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/shift
    const Username = listOfNames.shift();
    console.log('Current name:', Username);
    console.log(TestNames.length - listOfNames.length, ' names done.');
    console.log(listOfNames.length % TestNames.length, ' names left.')
  }
  else{
    //REM: Cancel the interval, if listOfNames has no more items
    clearInterval(interval);
    console.log('No names left.')
  }
}, 2000, Array.from(TestNames));

Take the names from an array or list and pass them to my variable. How can I do this ?

That depends on your requirements.

Do you need to keep TestNames?
Do you pick a random name?
Do you just pick the next name in order?

In my example I pass a copy of TestNames to the interval as listOfNames. On each iteration I remove the first item from listOfNames by using shift which also returns that removed item and assign it to Username. If listOfNames has no more items, the interval gets cleared.

Not my downvote. I prefer this one since it has no timeout and no pesky counter. — JavaScript, Jan 17 '23 at 09:55
@Gelegen the usernames are not random, I will set them myself. Which are then called up one after the other. TestNames was a example,can be changed — Jeffrey, Jan 17 '23 at 10:04

score 0 · Answer 2 · answered Jan 17 '23 at 09:25

0

const TestNames = ["test1", "test2", "test3", "test4", "test5"]

let index = 0

const interval = setInterval(function() {

  const Username = TestNames[index];

  console.log(Username);
  index += 1
}, 2000);


setTimeout(function() {
  clearInterval(interval)
}, 10000);

answered Jan 17 '23 at 09:25

Konrad

21,590
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Please: `index++` and what when it is manages to get to more than 4 before the clear? – mplungjan Jan 17 '23 at 09:26
@mplungjan `index++` is very complicated for beginners – Konrad Jan 17 '23 at 09:30
2

I disagree to teach beginners poor syntax. += is as difficult, Why not index = index + 1 if you want to be really simple? – mplungjan Jan 17 '23 at 09:34
Thanks for the many replies, I'll get to work right away and test them all :-) – Jeffrey Jan 17 '23 at 09:59
But here's another question, would ++, +=, +1 does everything work? What is bad syntax? – Jeffrey Jan 17 '23 at 10:06
@Jeffrey https://stackoverflow.com/questions/17241877/difference-between-and-1-in-javascript – Lain Jan 17 '23 at 10:10

score 0 · Answer 3 · answered Jan 17 '23 at 09:34

0

If you want to write a username for each iteration, I suggest this. Also note the use of const and let

const testNames = ["test1", "test2", "test3", "test4", "test5"]; // JS arrays starts at 0
const numberOfNames = testNames.length;
let counter = 0;
let interval = setInterval(function() { 
  if (counter >= numberOfNames) return; // don't continue
  let Username = testNames[counter];
  console.log(counter,Username); 
  counter++; // point at the next or perhaps beyond - shorthand for counter = counter + 1 or counter += 1.  ++ increments

  // here is some code                           
}, 2000);
let tId = setTimeout(function() {
  clearInterval(interval)
}, 10000);

answered Jan 17 '23 at 09:34

mplungjan

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Is there any reason for `interval` to be `let` and to assign `setTimeout` to `tId`? Just curious about the choice. – JavaScript Jan 17 '23 at 10:00
Using `++` is an antipattern for me. `testNames[counter++]` would make more sense. When you use `++` you imply that you care about the current value, but you want to increment it after. – Konrad Jan 17 '23 at 10:00
@Konrad while that is a stance to take, I entirely disagree. I totally dislike those **assign and use variable in same statement**. It is like using `testNames[index += 1]` in your snippet (if you start at -1). Also it may work in this case, yet it might not work generally if `counter` has more uses. – JavaScript Jan 17 '23 at 10:07
@JavaScript I always assign setInterval and setTimeout to separate variables. And I always assign them to a variable to be sure I can clear them if needed. – mplungjan Jan 17 '23 at 10:10
I was contemplating the [counter++] but I prefer to set it explicitly. In this case even more important because I wanted show the counter in the console.log BEFORE incrementing to teach SO that the JS Arrays started a 0. Also I ALWAYS use ++ when adding one to anything – mplungjan Jan 17 '23 at 10:12
2

Thanks again to everyone who helped :-) For my purposes, the code of "Gelegen" works best. Since I can always enlarge my array. So I don't need to know how many names are in it to calculate setTimeout. I like the counter function of "mplungJan". In the end I would know how many names I have without counting them myself. Now I'll try to see if I, as a beginner, can integrate the counter function in "Gelegen" his code :-) – Jeffrey Jan 17 '23 at 10:45

How to assign a value to a variable after each interval?

3 Answers3