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useValidTypeof (since v1.0.0)

Diagnostic Category: lint/suspicious/useValidTypeof

Sources:

This rule verifies the result of typeof $expr unary expressions is being compared to valid values, either string literals containing valid type names or other typeof expressions

Examples

Section titled Examples

Invalid

Section titled Invalid
typeof foo === "strnig"
suspicious/useValidTypeof.js:1:16 lint/suspicious/useValidTypeof ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  ✖ Invalid `typeof` comparison value
  
  > 1 │ typeof foo === "strnig"
      │                ^^^^^^^^
    2 │ 
  
  ℹ not a valid type name
  

typeof foo == "undefimed"
suspicious/useValidTypeof.js:1:15 lint/suspicious/useValidTypeof ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  ✖ Invalid `typeof` comparison value
  
  > 1 │ typeof foo == "undefimed"
      │               ^^^^^^^^^^^
    2 │ 
  
  ℹ not a valid type name
  

typeof bar != "nunber"
suspicious/useValidTypeof.js:1:15 lint/suspicious/useValidTypeof ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  ✖ Invalid `typeof` comparison value
  
  > 1 │ typeof bar != "nunber"
      │               ^^^^^^^^
    2 │ 
  
  ℹ not a valid type name
  

typeof bar !== "fucntion"
suspicious/useValidTypeof.js:1:16 lint/suspicious/useValidTypeof ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  ✖ Invalid `typeof` comparison value
  
  > 1 │ typeof bar !== "fucntion"
      │                ^^^^^^^^^^
    2 │ 
  
  ℹ not a valid type name
  

typeof foo === undefined
suspicious/useValidTypeof.js:1:16 lint/suspicious/useValidTypeof  FIXABLE  ━━━━━━━━━━━━━━━━━━━━━━━━━

  ✖ Invalid `typeof` comparison value
  
  > 1 │ typeof foo === undefined
      │                ^^^^^^^^^
    2 │ 
  
  ℹ not a string literal
  
  ℹ Unsafe fix: Compare the result of `typeof` with a valid type name
  
    1 │ typeof·foo·===·"undefined"
      │                +         +

typeof bar == Object
suspicious/useValidTypeof.js:1:15 lint/suspicious/useValidTypeof  FIXABLE  ━━━━━━━━━━━━━━━━━━━━━━━━━

  ✖ Invalid `typeof` comparison value
  
  > 1 │ typeof bar == Object
      │               ^^^^^^
    2 │ 
  
  ℹ not a string literal
  
  ℹ Unsafe fix: Compare the result of `typeof` with a valid type name
  
    1   │ - typeof·bar·==·Object
      1 │ + typeof·bar·==·"object"
    2 2 │   
  

typeof foo === baz
suspicious/useValidTypeof.js:1:16 lint/suspicious/useValidTypeof ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  ✖ Invalid `typeof` comparison value
  
  > 1 │ typeof foo === baz
      │                ^^^
    2 │ 
  
  ℹ not a string literal
  

typeof foo == 5
suspicious/useValidTypeof.js:1:15 lint/suspicious/useValidTypeof ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  ✖ Invalid `typeof` comparison value
  
  > 1 │ typeof foo == 5
      │               ^
    2 │ 
  
  ℹ not a string literal
  

typeof foo == -5
suspicious/useValidTypeof.js:1:15 lint/suspicious/useValidTypeof ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  ✖ Invalid `typeof` comparison value
  
  > 1 │ typeof foo == -5
      │               ^^
    2 │ 
  
  ℹ not a string literal

Valid

Section titled Valid
typeof foo === "string"
typeof bar == "undefined"
typeof bar === typeof qux
Section titled Related links