Classic task about for loop and setTimeout

forlooptask.md

What needs to be done to get the correct sequence of numbers from 0 to 4 inclusive?

for(var i = 0; i < 5; i++) {
    setTimeout(function() {
        console.log(i);
    }, 0)
}

---

Solutions:

1. Third parameter i in setTimeout as argument for handler

for(var i = 0; i < 5; i++) {
    setTimeout(function(i) {
        console.log(i)
   }, i*1000, i)
}

2. IIFE in setTimeout

for(var i = 0; i < 5; i++) {
    setTimeout((function(z) {
        return function() {
            console.log(z)
        }
    })(i), i * 1000)
}

3. IIFE out of setTimeout

for(var i = 0; i < 5; i++) {
    (function(z) {
        setTimeout(function(i) {
            console.log(z)
        }, i*1000)
     })(i)
}

4. With help of bind

for(var i = 0; i < 5; i++) {
    setTimeout((function(i) {
        console.log(i)
    }).bind(null, i), i*1000)
}

5. ES2015 approach (block scoped variable with let keyword )

for(let i = 0; i < 5; i++) {
    setTimeout(function() {
        console.log(i)
    }, i*1000)
}