Strange JavaScript behaviour? [closed]

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Closed 1 year ago.

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I have a simple function that calls other functions:

function update() {
 updateMissiles();
 updatePlayer;
 updateTurbines();
}

They are similar to each other in every way except updatePlayer will not run if I put brackets on the end of it. This doesn't break any code but I'm still curious why it does that?

• Dave Newton: Without knowing anything about updatePlayer, it's impossible to say much. But a function won't run unless it's called, and calling a function means ().
• Tadeck: @BogdanProtsenko: What is updatePlayer? What do you meand by "updatePlayer will not run" and how you check if it has been run?
• benekastah: What is your specific error message? My guess is that updatePlayer is not a function by the time update executes. Just before updatePlayer, write console.log(updatePlayer) to see what the value is.

Answer 1

I'm guessing there's an Exception in the updatePlayer method and since you're not calling it in the code you pasted above, you're not getting the Exception.

I would open up the Developer Tools for whatever browser you're using and see if there are any JavaScript Exceptions being thrown.

Answer 2

Without knowing more it's impossible to pinpoint exactly, but as a best guess - in the scope of the update function, the updatePlayer variable is not a function.

Try logging or debugging your javascript to find out what is going on.

Answer 3

A function will run only if you put () after it's name. If you don't put brackets you'll get the function's content. For example if you have:

function updatePlayer(){ alert('This is a player');}

And call it without brackets:

alert(updatePlayer);

the alerted output will be

function updatePlayer(){ alert('This is a player');}

This is used if you want to use callback functions.

Answer 4

You are confused. updatePlayer; doesn't invoke the updatePlayer function. updatePlayer(); does. Something else is going on in your code.