How do I enable strict mode in TypeScript?

[ghost]

I can't found option in Visual Studio for enable strict mode when compiling typescript to JS. Without this option Ecmascript 6 code not working in chrome, because required strict mode.

Uncaught SyntaxError: Block-scoped declarations (let, const, function, class) not yet supported outside strict mode

[DanielRosenwasser]

Just add "use strict" to the top of your file.

[ClaudenirFreitas]

IIFE with 'use strict';
(function() {
'use strict';
...
})();

[dharness]

Doesn't it seem a tad obtuse to add "use strict"; to every file? Is there any way to enforce strict mode in every file?

[kitsonk]

All ESM modules will automatically be interpreted in strict mode, as per the standard.

If the code you are compiling is to CJS, AMD or UMD, TypeScript automatically emits the 'use strict'; prolog in order to maintain the run-time compatibility with ESM.

If it is a "plain" non-modular file, then TypeScript is like JavaScript, in that it is an opt-in feature.

[mattmccutchen]

If anyone else finds this thread in a search, the latest status is that a compiler option to enable strict mode is planned (#10758).