JavaScript: Non-existent operators '=+', '=-' and '=!' should not be used

The use of operators pairs (=+, =- or =!) where the reversed, single operator was meant (+=, -= or !=) will compile and run, but not produce the expected results.

This rule raises an issue when =+, =- and =! are used without any space between the two operators and when there is at least one whitespace after.

Noncompliant Code Example

let target =-5;
let num = 3;

target =- num;  // Noncompliant; target = -3. Is that really what's meant?
target =+ num; // Noncompliant; target = 3

Compliant Solution

let target = -5;
let num = 3;

target = -num;  // Compliant; intent to assign inverse value of num is clear
target += num;