callback meaning javascript code example
Example 1: javascript callback
/*
A callback function is a function passed into another function
as an argument, which is then invoked inside the outer function
to complete some kind of routine or action.
*/
function greeting(name) {
alert('Hello ' + name);
}
function processUserInput(callback) {
var name = prompt('Please enter your name.');
callback(name);
}
processUserInput(greeting);
// The above example is a synchronous callback, as it is executed immediately.
Example 2: javascript callback
// Create a callback in the probs, in this case we call it 'callback'
function newCallback(callback) {
callback('This can be any value you want to return')
}
// Do something with callback (in this case, we console log it)
function actionAferCallback (callbackData) {
console.log(callbackData)
}
// Function that asks for a callback from the newCallback function, then parses the value to actionAferCallback
function requestCallback() {
newCallback(actionAferCallback)
}