Is there a typescript-eslint rule that alerts you when you use a method as a boolean?

问题

In Javascript, I sometimes accidentally write:

if (obj.method) {  // <-- bad
  ...
}

instead of

if (obj.method()) { // <-- good
  ...
}

Given that typescript-eslint is typeaware, is there a rule that detects this usage? I would say that 99/100 times, I am not trying to use the method as a boolean.

回答1:

If you turn on typescript's strictNullChecks compiler option (or the catch-all strict compiler option), TS will do this specific check for you automatically!

Example: https://www.typescriptlang.org/play/#code/CYUwxgNghgTiAEYD2A7AzgF3kgRgKwC54BveAWxAwAslgAKASiJySQhChXgF8AoXgJYAzeHVx4AdBWq0GJXvEXxe3IA

Otherwise as @x4rf41 mentioned in the comment, you can use a linter to catch it.
There are two typescript-eslint rules which will help you here:

• no-unnecessary-condition will ensure all your conditions are actually required (i.e. it would catch this case because the function is not nullable).
• strict-boolean-expressions will ensure all your if conditions are booleans (i.e. it would catch this case because the function is not a boolean).

来源：https://stackoverflow.com/questions/62826432/is-there-a-typescript-eslint-rule-that-alerts-you-when-you-use-a-method-as-a-boo