JSFiddle - React, Tailwind, and code Playground

JavaScript

var arr = [{"shares":50,"comments":10,"likes":0},{"likes":40,"shares":30,"comments":0},{"comments":10,"likes":0,"shares":0}];

var defaults = { "shares" : 0, "comments" : 0, "likes" : 0 };

arr = $.map( arr, function( item ){
    return $.extend( {}, defaults, item ); 
});

console.log( arr );