title: ESLint and snake_case inside TypeScript Type property
body: <p>I need to use snake_case for properties inside my Interfaces or Types. I set rule <code>camelcase</code> with</p>
  <pre><code>'camelcase': [&quot;error&quot;, {properties: &quot;never&quot;}],
  </code></pre>
  <p>as it <a href="https://eslint.org/docs/rules/camelcase" rel="nofollow noreferrer">mentioned in docs</a>. And it doesn't work for interfaces and types but works for JS objects.</p>
  <pre><code>export const test = {
      a_b: 1, // OK. No error
  };
  
  export interface ITest {
      a_b: number, // Identifier 'a_b' is not in camel case.eslint(camelcase)
  }
  
  export type TTest = {
      a_b: number, // Identifier 'a_b' is not in camel case.eslint(camelcase)
  }
  </code></pre>
  <p>Error is dissapears when I set the rule to <code>'off'</code>, so this rule applies to .ts files.</p>
  <p>So how can I use snake_case inside TS? Thanks.</p>