Bypasses for __proto__ string match

function insertPayload(original, payload) {
    let result = [];
    for (let i = 0; i <= original.length; i++) {
        let newString = original.slice(0, i) + payload + original.slice(i);
        result.push(newString);
    }
    return result;
}

s = "abc";
keys = insertPayload("__proto__", fromCodePoint($[i]))

for(i = 0; i < keys.length; i++) {
    if (typeof s[keys[i]] != "undefined") {
        log(keys[i]);
        break;
    }
}