Use a + with two numbers and you’ll get addition. But use it with a string and anything else, and you’ll get concatenation. This could
be confusing, especially if it’s not obvious that one of the operands is a string. It is recommended to explicitly convert the non-string component to
make it easier to understand to future maintainers.
This rule raises an issue when + or += is used with a string and a non-string.
Noncompliant code example
function foo() {
let x = 5 + 8; // okay
let z = "8"
return x + z; // Noncompliant; yields string "138"
}
Compliant solution
function foo() {
let x = 5 + 8;
let z = "8"
return x + Number(z);
}
