Enforce comparing typeof expressions against valid strings
The "extends": "eslint:recommended" property in a configuration file enables this rule
Some problems reported by this rule are manually fixable by editor suggestions
For a vast majority of use cases, the result of the typeof operator is one of the following string literals: "undefined", "object", "boolean", "number", "string", "function", "symbol", and "bigint". It is usually a typing mistake to compare the result of a typeof operator to other string literals.
This rule enforces comparing typeof expressions to valid string literals.
This rule has an object option:
"requireStringLiterals": true requires typeof expressions to only be compared to string literals or other typeof expressions, and disallows comparisons to any other value.Examples of incorrect code for this rule:
/*eslint valid-typeof: "error"*/
typeof foo === "strnig"
typeof foo == "undefimed"
typeof bar != "nunber"
typeof bar !== "fucntion"
Examples of correct code for this rule:
/*eslint valid-typeof: "error"*/
typeof foo === "string"
typeof bar == "undefined"
typeof foo === baz
typeof bar === typeof qux
Examples of incorrect code with the { "requireStringLiterals": true } option:
/*eslint valid-typeof: ["error", { "requireStringLiterals": true }]*/
typeof foo === undefined
typeof bar == Object
typeof baz === "strnig"
typeof qux === "some invalid type"
typeof baz === anotherVariable
typeof foo == 5
Examples of correct code with the { "requireStringLiterals": true } option:
/*eslint valid-typeof: ["error", { "requireStringLiterals": true }]*/
typeof foo === "undefined"
typeof bar == "object"
typeof baz === "string"
typeof bar === typeof qux
You may want to turn this rule off if you will be using the typeof operator on host objects.
This rule was introduced in ESLint v0.5.0.
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Licensed under the MIT License.
https://eslint.org/docs/latest/rules/valid-typeof