const arr = [];
const testObj = {};
console.log(arr === "");
console.log(arr == "");
arr.toString = () => 1;
console.log(arr === 1);
console.log(arr == 1);
arr.valueOf = () => 2;
console.log(arr == 2);
arr.valueOf = () => testObj;
console.log(arr == testObj); false true false true true false
false false false true false false
false true false false true true
false true true true true false