NativeScript/JavaScript Tip: Debugging

Once thing I was made aware of today was that not everyone knows the magic "debugger;" command.   I suppose this makes sense; I rarely see it mentioned, but it is a very useful debugging command in the JavaScript world.

The "debugger;" command is used to cause the application to stop and enter the debugger at that point.   This works in Node.js, the browsers, and even in NativeScript!    In a browser the developer tools must be open; if your debugger tools are closed; it will ignore it.     In node, a debugger must already be attached or it will also ignore it.

In NativeScript it will actually halt the program and WAIT until a debugger is attached!   So don't release your code

So pretend my code in main-page.js is

function pageLoaded(args) {
var page = args.object;
debugger;
// do something with the page object.
}

You can then start the application on the device; and it will automatically stop right at that debugger; statement.   Then at the command line type: tns run android --start and you will be in the debugger right at that line.

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