One liner flat object to key="value" conversion in ES6/ES2015 JavaScript

flat-object-to-key-value-string.js

// Any flat object with enumerable properties
var properties = {
  id: "myid",
  value: "myvalue"
};

// This prepends a space to each key. If you only need separators between add them in the join.
//                                                           ↓                                  ↓
var string = Object.keys(properties).map(function(n){return ` ${n}="${properties[n]}"`;}).join("");
// ' id="myid" value="myvalue"'