DataStructures_Dictionary_Associative_Array_in_JS.js

// Dictionary - Associative Array JS
function Dictionary() {
 this.datastore = new Array();
}

Dictionary.prototype.add = function(key, value) {
  this.datastore[key] = value;
}

Dictionary.prototype.find = function(key) {
  return this.datastore[key];
}

Dictionary.prototype.remove = function(key) {
  delete this.datastore[key];
}

Dictionary.prototype.showAll = function() {    
  for (var key of Object.keys(this.datastore)) {
    console.log(key + " -> " + this.datastore[key]);
  }
}

Dictionary.prototype.count = function() {
    var n = 0;
    for (var key of Object.keys(this.datastore)) {
        ++n;
    }
    return n;
}

Dictionary.prototype.clear = function() {
    for (var key of Object.keys(this.datastore)) {
        delete this.datastore[key];
    }
}

var pbook = new Dictionary();
pbook.add("Raymond","123");
pbook.add("David", "345");
pbook.add("Cynthia", "456");
console.log("Number of entries: " + pbook.count());
console.log("David's extension: " + pbook.find("David"));
pbook.showAll();
pbook.clear();
console.log("Number of entries: " + pbook.count());

//--- Result ---
/*
Number of entries: 3
David's extension: 345
Raymond -> 123
David -> 345
Cynthia -> 456
Number of entries: 0
*/