@putout/plugin-new
The new
operator lets developers create an instance of a user-defined object type or of one of the built-in object types that has a constructor function.
(c) MDN
🐊Putout plugin adds ability to add missing and remove useless operator new
.
Install
npm i @putout/plugin-new
Rule
{
"rules": {
"new/remove-useless": "on",
"new/add-missing": "on"
}
}
remove-useless
Operator new
has no sense for Boolean
, String
, Number
, Object
, RegExp
, Math
, Reflect
, Error
, TypeError
:
Thus the function call Error(…)
is equivalent to the object creation expression new Error(…)
with the same arguments.
(c) https://262.ecma-international.org/12.0/#sec-error-constructor
And Symbol
, BigInt
cannot be used with new
, as it is primitive.
❌ Example of incorrect code
new Error('Something whent wrong');
new new Boolean()();
✅ Example of correct code
Error('Something whent wrong');
Boolean();
add-missing
The Set
constructor lets you create Set objects that store unique values of any type, whether primitive values or object references.
(c) MDN
Missing operator new
should be added since built-in objects:
Set
;WeakSet
;Map
;WeakMap
;Int8Array
;Uint8Array
;Uint8ClampedArray
;Int16Array
;Uint16Array
;Int32Array
;Uint32Array
;Float32Array
;Float64Array
;BigInt64Array
;BigUint64Array
;
Produces TypeError
when called without new
:
Uncaught TypeError: Constructor Set requires 'new'
❌ Example of incorrect code
const map = Map();
✅ Example of correct code
const map = new Map();
Comparison
License
MIT