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Mike John
3,182 PointsWhy do we have to write the part func(arg) inside the function.?
Why do we have to write the part func(arg) inside the function.?
function weird(func,arg) {
func(arg) //Why do we use this over here
}
weird(function(something) {
console.log(something)}, "Greetings Everyone"
);
3 Answers
Tobiasz Gala
Full Stack JavaScript Techdegree Student 23,529 PointsThe point here is to understand that functions can be sent to other functions
function weird(func,arg) { // look at parameters - one is a function a one is a string
//In other words you have a function which needs a function and argument
func(arg) // here you call that function which was send as an argument function
//with a second argument
}
// here you call function an you pass anonymous function (with no name), and your string
weird(function(something) { console.log(something) }, "Greetings Everyone");
Let's change this example without anonymous function
// this function need function and string in order to work
function wierd(func, arg) {
// you call function which was send as an argument
// in this example you are sending someName() function
// and second argument from this function is passed to someName()
// which is 'Greetings Everyone'
func(arg); // equals someName('Greetings Everyone');
}
// this function is called when you call wierd() function
function someName(something) {
console.log(something);
}
// you call wierd() and pass someName() as first parameter, and string as second
wierd(someName(), 'Greetings Everyone');
Mike John
3,182 PointsThanks alot Tobiasz for such a detailed answer. I got much of the concept . But can you please tell me that why do we really need " func(arg) " .??? What if we leave it blank or do it like this:
function weird(func,arg){
function Goofy (something){console.log(something)} }
weird(Goofy(), "Greetings Everyone" );
Mike John
3,182 PointsAnd your Example without anonymous function does not works. Can you please tell why.?
Tobiasz Gala
Full Stack JavaScript Techdegree Student 23,529 Points[...]
// you call wierd() and pass someName() as first parameter, and string as second
wierd(someName, 'Greetings Everyone'); // mistake here, parentheses are used to call a function you don't use it when you pass its reference
Sorry made one mistake in my example. It is explained in the comment