[SOLVED] For loop with setTimeout

Question

I am trying to work with a for loop that sets a timeout on every string.
For example:

output first string after 1000ms
output second string after 2000ms
output third string after 3000ms
output fourth string after 4000ms
etc..
etc..

I made some code but didn't get it working..
Tried setTimeout inside the loop.
And tried to add a function so it loops throught the function.
What I am doing wrong🤔
Any help will be appericiated👍
(When solution is given, briefly explained will also be appericiated)

https://code.sololearn.com/WWWeQZEoYje2/?ref=app

Answer 1

the setTimeout method will run a function after some number of milliseconds, but only after the for loop has stopped executing, by the time the for loop has stopped executing, the value of i is 7. So each time the given function gets called, it will print out undefined because the value of len[7] is undefined so to get around this problem you have two choices either use the IIFE to capture i at each iteration like this:

for (var i=0, initialize=len.length; i<initialize; i++) {
(function(index){
setTimeout (function() {
document.write(" <span id='arrayvalue'>"+len[index]+"</span><br />");
}, 1000 * index);
})(i)
}

or simply use the let keyword instead of var:

for (let i=0, initialize=len.length; i<initialize; i++) {
setTimeout (function() {
document.write(" <span id='arrayvalue'>"+len[i]+"</span><br />");
}, 1000 * i);
}

Answer 2

replace 2000 by 2000*index

Answer 3

increase the time of the execution

Answer 4

Mohamed ELomari,

Thanks for the extended explanation to my question.
But I tried to capture each iteration with a callback function.

I tried the let keyword, but i cannot make changes to let when the code it running for later use to my understanding.
And tried the first solution you provided.
Both will not output first string, then second, then third after x amount of time between every output
Both will output the whole variable at once...

Answer 5

What is the reason to use *
I do not fully understand that part of the code