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function printFruits(fruits) {

  for (var i = 0; i < fruits.length; i++) {

    var curr = i;

    console.log(curr);

    setTimeout(function() {

      console.log(curr);

      console.log(fruits[curr]);

    }, i * 1000);

  }

}

printFruits(["Lemon", "Orange", "Mango", "Banana"]);
gurvinder372
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Ranjith Reddy Keesari
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  • What output are you getting and what is the expected one? – VTodorov Oct 24 '17 at 09:47
  • 1
    Possible duplicate of [How do I add a delay in a JavaScript loop?](https://stackoverflow.com/questions/3583724/how-do-i-add-a-delay-in-a-javascript-loop) and [JavaScript closure inside loops – simple practical example](https://stackoverflow.com/q/750486/4642212). – Sebastian Simon Oct 24 '17 at 09:48

1 Answers1

0

Value of curr will the one at the time of invocation and by that time value of curr has already reached 3.

You need to lock the value within a function.

(function(curr){setTimeout(function() {
  //console.log(curr);
  console.log(fruits[curr]);
}, i * 1000)})(curr);

Demo

function printFruits(fruits) 
{
  for (var i = 0; i < fruits.length; i++) 
  {
    var curr = i;
    //console.log(curr);
    (function(curr){setTimeout(function() {
      //console.log(curr);
      console.log(fruits[curr]);
    }, i * 1000)})(curr);
  }
}

printFruits(["Lemon", "Orange", "Mango", "Banana"]);
gurvinder372
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  • this is working fine, but how it is working that i am unable to understand can you please explain me. thanks in advance. – Ranjith Reddy Keesari Oct 24 '17 at 10:05
  • When the function is being defined current value of `curr` is passed to `setTimeout` via an **IIFE**. Now since `curr` has a local scope within the funciton, its value is not modified when the outer `curr` value is changed and hence it is locked for the execution of funciton. – gurvinder372 Oct 24 '17 at 10:08
  • @RanjithReddyKeesari Everything is explained in the two links I posted under your question. – Sebastian Simon Oct 24 '17 at 10:12
  • funcs[i] = (function(s) { console.log("My value: " + s); })(i) for (var j = 0; j < 3; j++) { funcs[j](); } – Ranjith Reddy Keesari Oct 24 '17 at 11:46