Type-checked loop conditions

[Rudxain]

Suggestion

There should be a tsconfig option to enable strict type-checking of loop condition predicates

🔍 Search Terms

while, loop, for, bool, boolean

✅ Viability Checklist

My suggestion meets these guidelines:

• This wouldn't be a breaking change in existing TypeScript/JavaScript code
• 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, new syntax sugar for JS, etc.)
• This feature would agree with the rest of TypeScript's Design Goals.

⭐ Suggestion

A tsconfig bool option named typeCheckedLoops (or something else) that throws an error when any condition isn't a boolean

📃 Motivating Example

I was surprised that TS allowed the following (even with very strict config):

while ("true");

while (!"");

while ([]);

for (;{};);

None of those are bools (except !""), yet they don't trigger any errors

💻 Use Cases

This becomes a problem when the condition is a variable, or an expression composed of multiple vars.

[MartinJohns]

Essentially a duplicate of #38826.

[Rudxain]

Thank you for the info. I'll close this