Ng-app vs. data-ng-app, what is the difference?

Directive normalization: ng- vs. data-ng-

AngularJS employs a mechanism termed directive normalization. To put it simply, this is a conversion process transforming attribute names into a standard or canonical format. Thanks to normalization, AngularJS users can interchangeably use different prefixes like ng:, ng_, x-ng-, and naturally, data-ng-.

AngularJS performs an internal makeover for data-ng- and x-ng- prefix, stripping away the data- and x- prefixes and subsequently converting the name into camelCase. This move achieves normalization. For instance:

• The cool kid data-ng-bind turns out to be ngBind
• The mysterious rogue x-ng-bind transfigures into ngBind
• The brooding loner ng:bind morphs into ngBind

For devout followers of the HTML5 dogma, it's recommended to prefix AngularJS attributes with a well-rounded data-. You'll have the final laugh when your HTML code successfully navigates through the fiery ordeal of HTML validation probes, as per HTML5's stern directive downright insisting on custom attributes prefixed with data-.

Compliant mascots: ng- and data-ng-

Here's a question worth pondering over in your journey as a developer: Is your heart pounding in rhythm with HTML compliance? If the answer leans toward affirmative, the data-ng-app attribute steps up as your trustworthy sidekick. Now, if you're more of a maverick wandering freely in an environment devoid of HTML validation shackles, you can still use ng-app without any worry.

The "data- supremacy" plays out especially well in scenarios where older HTML validators crash the party or you find yourself under the glaring spotlight of SEO, demanding nothing short of fully-compliant HTML markup. Embrace data-ng-app with open arms and dodge potential issues with old-school tools lacking even basic camaraderie with the HTML5 spec.

Directive prefixes: What to choose and when?

Regular development routine with no penalty for validation disregard:

• ng-app is your buddy. Call him up if there's no strict enforcer like HTML validation testing your limits.

Projects driven by HTML5 standards and rigorous compliance:

• Go on a coffee date with data-ng-app. Not only will it help you score full points in the validation tests, it will also render full AngularJS services at your disposal.

Tooling and managed integration scenarios:

• If AngularJS is a tiny cog in your larger-than-life project encompassing other vital organs like HTML validators, data-ng-app can nip nagging validation issues in the bud and emerge as the shield that fortresses your development process.

In-depth: Beyond HTML validation

Performance considerations:

• The choice between ng-app and data-ng-app is primarily about validation. Rest assured, no performance differences lurk in their duality.

Code readability and team synergy:

• Consistent adoption of the data- prefix enhances readability and signals compliant code throughout the application, aiding team collaboration.

Ensuring maintainability:

• Consistency is king — commit to a single style for directive prefixes across your AngularJS codebase (preferably data-ng-) to simplify maintenance and faster bring on board new developers.