This is a playground to test JavaScript. It runs a completely standard copy of Node.js on a virtual server created just for you. Every one of npm’s 300,000+ packages are pre-installed, so try it out:
/*
// First Try, FAIL: Prints `1 2 3 4 5` all at once, after 2 seconds
for (let i = 1; i <= 5; i++) {
setTimeout( () => { console.log(i) }, 2000); // All iterations are logged to console at +2000ms
}
*/
/*
// Second Try, FAIL: Prints `6 6 6 6 6` one after the other, every 2 seconds
for (var i = 1; i <= 5; i++) { // Traditional `var`
setTimeout(function() { console.log(i); }, 2000 * i); // Traditional function
}
*/
/*
// Third Try, SUCCESS: Prints `1 2 3 4 5` one after the other, every 2 seconds
// Closure
for (var i = 1; i <= 5; i++) { // Traditional `var`
(function(x) {
setTimeout(function() {
console.log(x);
}, 2000 * x); // Traditional function
})(i);
}
*/
/*
// Fourth Try, SUCCESS
// ES6 `let`
for (let i = 1; i <= 5; i++) { // ES6 `let`
setTimeout(function() { console.log(i); }, 2000 * i); // Traditional function
}
*/
/*
// Variation: with arrow function
for (let i = 1; i <= 5; i++) { // ES6 `let`
setTimeout(() => { console.log(i); }, 2000 * i); // ES6 arrow function
}
*/
/*
// Fifth Try, FAIL: Prints `1 2 3 4 5` all at once
// Recursion
var i = 1;
(function CountToFive() {
setTimeout(function () {
while (i <= 5) { // Using `while` breaks the code
console.log(i);
i++;
}
CountToFive();
}, 2000);
})();
*/
/*
// Sixth Try, SUCCESS
// Recursion
var i = 1;
(function CountToFive() {
setTimeout(function () {
if (i <= 5) { // Using `if` makes it work
console.log(i);
i++;
}
CountToFive();
}, 2000);
})();
*/
/*
// Seventh Try, SUCCESS
// Verbose: with two extra function calls within `setTimeOut()`
(function CountToFive() {
for (let i = 1; i <= 5; i++) {
setTimeout(function(x) {
return function() { console.log(x); };
}(i), 2000 * i);
}
})();
*/
// Eighth try, SUCCESS
// Recursion With Stop
var i = 1;
(function CountToFive() {
let timer = setTimeout(function () {
if (i <= 5) { // Using `if` makes it work
console.log(i);
i++;
} else {
clearTimeout(timer); // Stops timer if `i` reaches 5
}
CountToFive();
}, 2000);
})(i);
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