CODEWITHSUNDEEP
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H Dennis
H Dennis

Reputation: 1

Calling function from external .js file, nothing happens

I have a really basic JavaScript project, I'm just testing out and learning the language. All I want the program to do is launch and call a function inside the external main.js file. At the moment nothing happens on launch.

I have tried copying examples given online but they don't seem to be working for me.

HTML File:

<!DOCTYPE html>
<html>
<head>
    <meta charset="utf-8" />
    <title>Cex_Program</title>
    <link href="css/default.css" rel="stylesheet" />
</head>
<body>
    <div>Content goes here!</div>
    <script src="js/main.js"></script>
    <script>
        Main();
    </script>
</body>
</html>

JavaScript file:

Content of function is irrelevant, I just want the program flow to enter the function (hit my breakpoint);

// Your code here!

var InfiniteLoop = 1;
var DeltaTime = 0;

function Main()
{
    var Day = new Date();
    var StartTime = Math.round(new Date() / 1000);
    var StartCurrentLoopTime = 0;
    var EndCurrentLoopTime = 0;
}

Upvotes: 0

Views: 453

Answers (2)

Fred Gandt
Fred Gandt

Reputation: 4312

This does work

<!DOCTYPE html>
<html>
  <body>
    <div>Content goes here!</div>
    <script>function Main( str ) { console.log( str ); }</script>
    <script>
        Main( "Main!" );
    </script>
  </body>
</html>

So

We can deduce from this that either js/main.js is not being downloaded, the function Main() is inaccessible to a <script> outside it or that Main() simply doesn't function or produce a discernable result.

See this w3schools tutorial about scopes for more details on why Main() might be inaccessible.

Check your browser's console for errors in the case of Main() not functioning.

I will happily update this answer as needed in response to positive feedback.

To test if Main() is accessible

Check if Main() is a global function by finding out if window.hasOwnProperty( "Main" ) before typing to use it.

<!DOCTYPE html>
<html>
  <body>
    <div>Content goes here!</div>
    <script>
        ( function() {
            function Main( str ) { console.log( str ); }
        } () );
        function Alt( str ) { console.log( str ); }
    </script>
    <script>
        if ( window.hasOwnProperty( "Main" ) ) {
            Main( "Main!" );
        } else {
            console.error( "Main() can't be accessed from here" );
            if ( window.hasOwnProperty( "Alt" ) ) {
                Alt( "Alt!" );
            }
        }
    </script>
  </body>
</html>

Upvotes: 3

LeDoc
LeDoc

Reputation: 945

I created your setup on my dev machine and loaded the html page. Assuming the files are named correctly on your machine, I can confirm that the code did execute.

A good way to check if JavaScript is running correctly in the browser is to use a debugger:

Upvotes: 0

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