Use a + with two numbers and you'll get addition. But use it with a string and anything else, and you'll get concatenation. Very often
that's not what's intended.
Since this may not be what's intended, this rule raises an issue when + is used with a string and a non-string.
var x = 5 + 8; // okay var z = "8" var y = 5 + z; // Noncompliant; yields string "58"
var x = 5 + 8; var z = "8"; var y = 5 + Number(z);