JSFiddle - React, Tailwind, and code Playground

JavaScript

var row = {
        'entity' : {
                  'fileAttribute' : {
                      '.\K\ar- #%i\.n/a': true,
                      'size': '20',
                      'qty' : '50'
                      },
                  'part2' : {
                      'name': 'Part 2',
                      'size': '15',
                      'qty' : '60'
                  }
				}
		};

console.log( row.entity.fileAttribute['.\K\ar- #%i\.n/a'] );