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[no-undef] No-undef error on user-defined Typescript type guards #2462

victorgarciaesgi opened this issue Sep 1, 2020 · 3 comments


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@victorgarciaesgi victorgarciaesgi commented Sep 1, 2020

  • I have tried restarting my IDE and the issue persists.
  • I have updated to the latest version of the packages.
  • I have read the FAQ and my problem is not listed.


  "rules": {
    '@typescript-eslint/no-useless-constructor': 'error',
    '@typescript-eslint/no-unused-vars': 'off',
    '@typescript-eslint/explicit-function-return-type': 'off',
    '@typescript-eslint/no-explicit-any': 'off',
    '@typescript-eslint/no-use-before-define': 'off',
    '@typescript-eslint/interface-name-prefix': 'off',
    '@typescript-eslint/no-var-requires': 'off',
    '@typescript-eslint/no-namespace': 'off',
    '@typescript-eslint/camelcase': 'off',
    '@typescript-eslint/no-empty-function': 'off',
    '@typescript-eslint/ban-ts-ignore': 'off',
    '@typescript-eslint/explicit-module-boundary-types': 'off',
    '@typescript-eslint/ban-ts-comment': 'off',
    '@typescript-eslint/no-non-null-assertion': 'off',
export default class Column extends Vue {
  isColumnString(column: TableColumn): column is string {
                                   //   ^^^^^ 'column' is not defined (eslint: no-undef)
    return typeof this.column === 'string';

Expected Result

Actual Result


package version
@typescript-eslint/eslint-plugin 4.0.1
@typescript-eslint/parser 4.0.1
TypeScript 4.0.2
ESLint 7.8.0
node 12.18.0
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@jacekkarczmarczyk jacekkarczmarczyk commented Sep 1, 2020

Is this bug related/duplicate?

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@vvscode vvscode commented Sep 2, 2020

@jacekkarczmarczyk in fact it's another problem, but it might be caused with same reason

@bradzacher bradzacher self-assigned this Sep 5, 2020
@bradzacher bradzacher added the has pr label Sep 5, 2020
bradzacher added a commit that referenced this issue Sep 5, 2020
Fixes #2462
bradzacher added a commit that referenced this issue Sep 5, 2020
Fixes #2462
phaux added a commit to phaux/typescript-eslint that referenced this issue Sep 28, 2020
@github-actions github-actions bot locked as resolved and limited conversation to collaborators Oct 6, 2020
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