JSFiddle - React, Tailwind, and code Playground

JavaScript

$(function(){
   
    var item= {  "COLUMNS": [  "username", "password" ],
                 "DATA": [    [ "foo", "bar"  ] ,[ "foo2", "bar2"  ]]
              }
        console.debug(item.COLUMNS[0])
        console.debug(item.COLUMNS[1])
    $.each(item.DATA, function(index,item) {        
        console.debug(item[0])
        console.debug(item[1])
        });
    
});