Note: – It is similar to the values() in case of Sets It is a highly flexible tool, built upon the foundations of progressive enhancement, that adds all of these advanced features to any HTML table. HTML5 is designed with extensibility in mind for data that should be associated with a particular element but need not have any defined meaning. DataTables is a plug-in for the jQuery Javascript library. arr = { date:'222222' } lines = [ { line1:'line1' , name:'paul' } , { line2:'line2' , name:'john' } , ] arr.push( lines ) I want to send arr to handlebars but need the lines adding to arr . Set.prototype.keys() Returns a new iterator object that yields the values for each element in the Set object in insertion order. The first thing we need to do is to grab the HTML element so we can access it’s properties. QUICK NOTES. The dataset property on the HTMLElement interface provides read/write access to all the custom data attributes (data-*) set on the element. In the case of datasets such as the wholesale customer dataset (covered later in the book), where we don't have final labels, the results of clustering cannot be objectively verified and therefore might lead to misguided conclusions. Set.prototype.keys() – It also returns all the values from the Set in the insertion order. The