📝 VSCode Output Channels

An output channel is a way to display information to the user of an extension. Logging data to an output channel is similar to logging information, but outputChannel.appendLine is used instead of console.log.

The output channel must be shared between function calls. In case the creation of an output channel is part of the command execution, a new output channel is created every time a command is executed and the old one isn’t automatically reused or removed.

vscode.commands.registerCommand requires passing a function, which means you can’t define the input to the function at that time. This can be solved by calling the function in a lambda:

export function activate(context: vscode.ExtensionContext) {
    const validateRepoOutputChannel = vscode.window.createOutputChannel("Validate Repo");
 
    context.subscriptions.push(
        vscode.commands.registerCommand('blogging.validateRepo', () => {
            functions.validateRepo(validateRepoOutputChannel);
        })
    );
}

Preserving focus

The default behaviour when showing an output channel is to grab focus, which is not what I expected. To prevent the output channel from grabbing focus, add true as input to show (e.g., outputChannel.show(true)).