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ja5on
10,338 PointsPassing a function as an argument.
function sayHello() {
return "Hello, ";
}
function greeting(helloMessage, name) {
console.log(helloMessage() + name);
}
greeting(sayHello, "JavaScript!");
I can tell helloMessage is an arugument but could someone tell me what helloMessage() is please, because its not a function as I can see?
My guess would be that it's a call its itself?? Thats just a wild guess...
1 Answer
Juan Luna Ramirez
9,038 PointsThe value of helloMessage should be a function because that's how you are using it in greeting. So in your example, the value of sayHello, a function, becomes the value of helloMessage when running greeting(sayHello, "Javacript!"). So it all works out.
But lets say I did not use a function as the fist argument. Say I did greeting("hello", "Javascript!"). In this case, helloMessage becomes "hello", a string . This would result in a syntax error because you can't run a string.
In other words, helloMessage becomes whatever you pass into the function when you run the function.