How to add a key/value to an object?

Question

JavaScript

I will parse html . In html there are ul>li lists, I will add the key is the text ul , and the value is li , but I can’t figure out how to add them to the object.
What is the cat method that creates a new key and value?
// a piece of code does not parse html , but will give an understanding of how to do it . Thank you!

var obj = {};
var mass = ['Number1', 'Number2'];
  for(var i=0; mass.length; i++){

  }
// Как сделать такой объект
obj = {
  Number1 = '0';
  Number2 = '1'
}

Answer 1

obj[mass[i]] = i