So I was doing some practice about callback function and I wanted to try it out in my own was and use it with a setTimeout Method and to my surprise, it didn't work as expected.. Pls what am i doing wrong here.
function first(number, callback) {
setTimeout(function() {
console.log(number);
}, 5);
callback();
}
function second() {
console.log(2);
}
first(1, second);You're executing setTimeout and callback at the same time. Because JavaScript is single-threaded, it doesn't wait for setTimeout to complete before executing the next statement.
That's why, 2 prints immediately, and then 1 prints after a delay of 5 milliseconds.
If you want to print 1 first, then you need to call the callback function in the callback of setTimeout. This ensures that the console.log(number) executes prior to calling the callback (which prints 2).
function first(number, callback) {
setTimeout(function() {
console.log(number);
callback();
}, 5);
}
function second() {
console.log(2);
}
first(1, second);As 31piy already said, setTimeout() and callback() are being executed at the same time. Your code first schedules a function execution at 5ms from now, and then immediately runs another function that logs 2 to the console.
You can achieve the expected result in a couple of similar ways, I'll show one:
function first(number,callback) {
setTimeout(function() {
callback();
}, 5);
console.log(number);
}
function second() {
console.log(2);
}
first(1, second);
//Here, you immediately print the number 1 and schedule the number 2.
