strict boolean expressions compilerOption

Search Terms

require strict boolean

Suggestion

add yet another --strict check into compilerOptions, to only allow expressions that evaluate to Boolean for all conditional branching - if, for, while, ?: ternary operator, etc

basically this TSLint rule, built into TS compiler
https://palantir.github.io/tslint/rules/strict-boolean-expressions/

Use Cases

often people check the existence of function, before calling it:
if (somFunc) someFunc()

or they think that function is actualy a property, and hence dont call it

if (someVal)... . where it should have been if (someVal()) ...

if if required a strict boolean expression, both of the above would have been errors.

Examples

instead above examples would be written:
if (!!someFunc) someFunc()

and for someValue():boolean

if (someValue())..

Checklist

My suggestion meets these guidelines:

• This wouldn't change the runtime behavior of existing JavaScript code
• This could be implemented without emitting different JS based on the types of the expressions
• This isn't a runtime feature (e.g. library functionality, non-ECMAScript syntax with JavaScript output, etc.)
• This feature would agree with the rest of TypeScript's Design Goals.

Beginne mit der Überprüfung von TypeScripts Verarbeitung von compilerOptions und der Pfade der Typprüfung für if, for, while und bedingte Ausdrücke. Vergleiche das gewünschte Verhalten mit der verknüpften TSLint-Regel strict-boolean-expressions. Erledigt ist es, wenn eine Compileroption bedingte Ausdrücke mit booleschem Wert erzwingt, ohne das erzeugte JavaScript zu ändern.