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Rslint

    init-declarations

    Added in v0.8.1

    Configuration

    rslint.config.ts
    import { defineConfig, js } from '@rslint/core';

export default defineConfig([
  js.configs.recommended,
  {
    rules: {
      'init-declarations': 'error',
    },
  },
]);

    Rule Details

    Require or disallow initialization in variable declarations.

    This rule applies to var, let, const, using, and await using declarations. It reports each declarator whose initialization does or does not match the configured mode.

    Examples of incorrect code for this rule with "always" (the default):

    function foo() {
  var bar;
  let baz;
}

    Examples of correct code for this rule with "always":

    function foo() {
  var bar = 1;
  let baz = 2;
  const qux = 3;
}

    Examples of incorrect code for this rule with "never":

    { "init-declarations": ["error", "never"] }
    function foo() {
  var bar = 1;
  let baz = 2;
  for (let i = 0; i < 1; i++) {}
}

    Examples of correct code for this rule with "never":

    function foo() {
  var bar;
  let baz;
  const buzz = 1;
}

    const, using, and await using declarations always require an initializer, so "never" never flags them.

    Examples of correct code for this rule with { "ignoreForLoopInit": true }:

    { "init-declarations": ["error", "never", { "ignoreForLoopInit": true }] }
    for (let i = 0; i < 1; i++) {}

    A destructuring declarator (var { a } = obj;, var [a] = arr;) is never reported, in either mode.

    declare var/declare let/declare const, and any declaration nested inside a declare namespace/declare module/ambient .d.ts context, is exempt in both modes.

    Options

    This rule takes up to two options:

    1. A string, either "always" (default) or "never".
    2. When the first option is "never", an object with:
      • ignoreForLoopInit: when true, allows initialization in a for loop's declaration even under "never". Default false.

    Original Documentation