i want to get lastmonth like 122023 as a result, how to achieve this?

I have no idea what you're asking for, but this is a solution to the problem as stated, which I'm sure is not the problem you're trying to solve.

function getLastMonthString(){
    var then = new Date();
    then.setDate(0);
    return `${then.getMonth()+1}${then.getFullYear()}`;
}

I don’t think that works?

Ah, I get it, sorry.

umm apology accepted? 😄

moment.js