How to disable a ts rule for a specific line?

Question

As of Typescript 2.6, you can now bypass a compiler error/warning for a specific line:

if (false) {
    // @ts-ignore: Unreachable code error
    console.log("hello");
}

Note that the official docs "recommend you use [this] very sparingly". It is almost always preferable to cast to any instead as that better expresses intent.

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Older answer:

You can use /* tslint:disable-next-line */ to locally disable tslint. However, as this is a compiler error disabling tslint might not help.

You can always temporarily cast $ to any:

delete ($ as any).summernote.options.keyMap.pc.TAB

which will allow you to access whatever properties you want.

@ts-expect-error

TypeScript 3.9 introduces a new magic comment. @ts-expect-error will:

• have same functionality as @ts-ignore
• trigger an error, if actually no compiler error has been suppressed (= indicates useless flag)

if (false) {
  // @ts-expect-error: Let's ignore a compile error like this unreachable code 
  console.log("hello"); // compiles
}

// If @ts-expect-error didn't suppress anything at all, we now get a nice warning 
let flag = true;
// ...
if (flag) {
  // @ts-expect-error
  // ^~~~~~~~~~~~~~~^ error: "Unused '@ts-expect-error' directive.(2578)"
  console.log("hello"); 
}

Playground

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What do TypeScript developers recommend?

@ts-ignore and @ts-expect-error are like a sledgehammer for compile errors. TypeScript developers recommend more fine-grained, narrow-scoped typesystem solutions for most cases:

We added ts-ignore with the intent that it be used for the remaining 5% that can't be suppressed by any existing type system mechanics [...] there should be very very very few ts-ignores in your codebase[.] - microsoft/TypeScript#19139

[...] fundamentally, we believe you shouldn't be using suppressions in TypeScript at all. If it's a type issue, you can cast out of it (that's why any, casting, and shorthand module declarations exist). If it's a syntax issue, everything is awful and we'll be broken anyway, so suppressions won't do anything (suppressions do not affect parse errors). - microsoft/TypeScript#19573

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Alternatives for question-case

▶ Use any type

// type assertion for single expression
delete ($ as any).summernote.options.keyMap.pc.TAB;

// new variable assignment for multiple usages
const $$: any = $
delete $$.summernote.options.keyMap.pc.TAB;
delete $$.summernote.options.keyMap.mac.TAB;

▶ Augment JQueryStatic interface

// ./global.d.ts
interface JQueryStatic {
  summernote: any;
}

// ./main.ts
delete $.summernote.options.keyMap.pc.TAB; // works

In other cases, shorthand declarations / augmentations are handy utilities to compile modules with no / extendable types. A viable strategy is also to incrementally migrate to TypeScript, keeping not yet migrated code in .js via allowJs and checkJs: false compiler flags.

You can simple use the following just before the line: // @ts-ignore