This answer is good for typescript / Angular 2, 4, 5+
I got this answer with the help of @rujmah answer above. His answer brings in the array count... and then find's the value and replaces it with another value...
What this answer does is simply grabs the array name that might be set in another variable via another module / component... in this case the array I build had a css name of stay-dates. So what this does is extract that name and then allows me to set it to another variable and use it like so. In my case it was an html css class.
let obj = this.highlightDays.find(x => x.css);
let index = this.highlightDays.indexOf(obj);
console.log('here we see what hightlightdays is ', obj.css);
let dayCss = obj.css;
