CODEWITHSUNDEEP
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ichachan
ichachan

Reputation: 667

setTimeout Never Executes Function 2

I tried to write asynchronous function calls in javascript using setTimeout

function async(fn, callback) {
setTimeout(function () {
    fn();
    callback();
}, 1000);
}

This is how the function is being called. I want function foo() to run first, and then my next function. Foo() runs successfully but the next function never comes out. Any idea?

async(foo(), function () {
    var check = checkField();
    alert('Check: ' + check); //somehow never comes out
});

Upvotes: 0

Views: 371

Answers (2)

Bharel
Bharel

Reputation: 26901

You should pass foo instead of calling it while calling async:

async(foo, function () {
var check = checkField();
alert('Check: ' + check); //somehow never comes out
});

Upvotes: 2

Rafael
Rafael

Reputation: 18522

You're calling foo in a synchronous way, because instead of passing a reference to foo to the async function, you're calling foo and passing to async the result of foo, which is probably undefined (although just guessing here, because I don't know how foo looks like), so when the timeout hits and async tries to call fn it throws error that undefined is not a function and thus never reaches the line that calls the second callback. You should call async this way:

async(foo, function () {
    var check = checkField();
    alert('Check: ' + check);
});

Upvotes: 2

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