ESLintenforce comparing typeof expressions against valid strings (valid-typeof)
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" and "symbol". It is usually a typing mistake to compare the result of a typeof operator to other string literals.
Rule Details
This rule enforces comparing typeof expressions to valid string literals.
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
When Not To Use It
You may want to turn this rule off if you will be using the typeof operator on host objects.
Version
This rule was introduced in ESLint 0.5.0.