Develop Reference

Get a value of a HashTable

I was making a HashTable to have as an example and have it saved for any problem, but I ran into a problem trying to implement a method that returns true or false in case the value belongs to the HashTable, since it is inside a arrays of objects as comment in the code.
I have tried for loops, .map and for of, but it always fails, if someone could help me.
function HashTable () {
this.buckets = [];
this.numbuckets = 35;
}
HashTable.prototype.hash = function (key) {
let suma = 0;
for (let i = 0; i < key.length; i++) {
suma = suma + key.charCodeAt(i);
}
return suma % this.numbuckets;
}
HashTable.prototype.set = function (key, value) {
if (typeof key !== "string") {
throw new TypeError ("Keys must be strings")
} else {
var index = this.hash(key);
if(this.buckets[index] === undefined) {
this.buckets[index] = {};
}
this.buckets[index][key] = value;
}
}
HashTable.prototype.get = function (key) {
var index = this.hash(key);
return this.buckets[index][key];
}
HashTable.prototype.hasKey = function (key) {
var index = this.hash(key);
return this.buckets[index].hasOwnProperty(key)
}
HashTable.prototype.remove = function (key) {
var index = this.hash(key);
if (this.buckets[index].hasOwnProperty(key)) {
delete this.buckets[index]
return true;
}
return false;
}
HashTable.prototype.hasValue = function (value) {
let result = this.buckets;
result = result.flat(Infinity);
return result // [{Name: Toni}, {Mame: Tino}, {Answer: Jhon}]
}

You can use Object.values() to get the values of all the propertyies in the bucket.
function HashTable() {
this.buckets = [];
this.numbuckets = 35;
}
HashTable.prototype.hash = function(key) {
let suma = 0;
for (let i = 0; i < key.length; i++) {
suma = suma + key.charCodeAt(i);
}
return suma % this.numbuckets;
}
HashTable.prototype.set = function(key, value) {
if (typeof key !== "string") {
throw new TypeError("Keys must be strings")
} else {
var index = this.hash(key);
if (this.buckets[index] === undefined) {
this.buckets[index] = {};
}
this.buckets[index][key] = value;
}
}
HashTable.prototype.get = function(key) {
var index = this.hash(key);
return this.buckets[index][key];
}
HashTable.prototype.hasKey = function(key) {
var index = this.hash(key);
return this.buckets[index].hasOwnProperty(key)
}
HashTable.prototype.remove = function(key) {
var index = this.hash(key);
if (this.buckets[index].hasOwnProperty(key)) {
delete this.buckets[index]
return true;
}
return false;
}
HashTable.prototype.hasValue = function(value) {
return this.buckets.some(bucket => Object.values(bucket).includes(value));
}
let h = new HashTable;
h.set("Abc", 1);
h.set("Def", 2);
console.log(h.hasValue(1));
console.log(h.hasValue(3));

JavaScript For Loop does not return

My problem is that a loop that is called in another for loop and should return an object does not return anything. When I set a breakpoint to the return statement the object is there but undefined in my callback function. types object is a global object that contains many objects as properties with the properties "title" and "id".
function searchObj(obj, query) {
for (var key in obj) {
var value = obj[key];
if (typeof value === 'object') {
searchObj(value, query)
}
if (value === query) {
return obj;
}
}
}
The function is called from here:
function callback(data){
var logs = [];
var results = data.d.results;
for (var i = 0; results.length; i++) {
var item = results[i];
var action = util.searchObj(types, item.ActionId);
var obj = {
'Created': item.Created,
'Text': String.format(action.title, item.Author.Title),
'Author': item.Author
}
logs.push(obj);
}
console.log(logs);
}

Try this:
function searchObj(obj, query) {
for (var key in obj) {
var value = obj[key];
if (typeof value === 'object') {
var result = searchObj(value, query);
if (result) {
return result;
}
}
if (value === query) {
return obj;
}
}
}

JavaScript: Invalid destructuring target

Here is the code:
function BinarySearchNode(key) {
let node = {};
node.key = key;
node.lft = null;
node.rgt = null;
node.log = () => {
console.log(node.key);
}
node.get_node_with_parent = (key) => {
let parent = null;
while (this) {
if (key == this.key) {
return [this, parent];
}
if (key < this.key) {
[this, parent] = [this.lft, this];
} else {
[this, parent] = [this.rgt, this];
}
}
return [null, parent];
}
return node;
}
My Firefox is 44.0 and it throws a SyntaxError for these lines:
if (key < this.key) {
[this, parent] = [this.lft, this];
} else {
I tried to understand what exactly is wrong here by reading this blogpost and the MDN. Unfortuntely, I am still missing it :(

this is not a variable, but a keyword and cannot be assigned to. Use a variable instead:
node.get_node_with_parent = function(key) {
let parent = null;
let cur = this; // if you use an arrow function, you'll need `node` instead of `this`
while (cur) {
if (key == cur.key) {
return [cur, parent];
}
if (key < cur.key) {
[cur, parent] = [cur.lft, cur];
} else {
[cur, parent] = [cur.rgt, cur];
}
}
return [null, parent];
}

Readability of Javascript Array

I have a JSON OBJECT similar to following
{
"kay1":"value1",
"key2":"value2",
"key3":{
"key31":"value31",
"key32":"value32",
"key33":"value33"
}
}
I want to replace that with JSON ARRAY as follows
[
"value1",
"value2",
[
"value31",
"value32",
"value33"
]
]
My motivation to change the the JSON OBJECT to JSON ARRAY is it takes less amount of network traffic, getting the value from ARRAY is efficient than OBJECT, etc.
One problem I face is the readability of the ARRAY is very less than OBJECT.
Is there any way to improve the readability?

Here you go, I have written a function which will convert all instances of object to array and give you the result you are expecting.
var objActual = {
"key1":"value1",
"key2":"value2",
"key3":{
"key31":"value31",
"key32":"value32",
"key33": {
"key331" : "value331",
"key332" : "value332"
}
}
};
ObjectUtil = {
isObject : function(variable) {
if(Object.prototype.toString.call(variable) === '[object Object]') {
return true;
}
return false;
},
convertToArray : function(obj) {
var objkeys = Object.keys(obj);
var arr = [];
objkeys.forEach(function(key) {
var objectToPush;
if(ObjectUtil.isObject(obj[key])) {
objectToPush = ObjectUtil.convertToArray(obj[key]);
} else {
objectToPush = obj[key];
}
arr.push(objectToPush);
});
return arr;
}
};
var result = ObjectUtil.convertToArray(objActual);
console.log(result);

In my opinion, it should be:
{
"kay1":"value1",
"key2":"value2",
"key3":["value31", "value32", "value33"]
}

Using the init method is time critical. So use a scheme or assign static JSON to Storage.keys and assign your bulk data array to store.data. You can use store.get("key3.key31") after that. http://jsfiddle.net/2o411k00/
if (!Array.prototype.map)
{
Array.prototype.map = function(fun /*, thisp*/)
{
var len = this.length;
if (typeof fun != "function")
throw new TypeError();
var res = new Array(len);
var thisp = arguments[1];
for (var i = 0; i < len; i++)
{
if (i in this)
res[i] = fun.call(thisp, this[i], i, this);
}
return res;
};
}
var data = {
"kay1":"value1",
"key2":"value2",
"key3":{
"key31":"value31",
"key32":"value32",
"key33":"value33"
}
}
var Storage = function(data){
this.rawData = data;
return this;
}
Storage.prototype.init = function(){
var self = this;
var index = 0;
var mp = function(dat, rootKey){
var res = Object.keys(dat).map(function(key, i) {
var v = dat[key];
if (typeof(v) === 'object'){
mp(v, key);
} else {
self.data.push(v);
var nspace = rootKey.split(".").concat([key]).join(".");
self.keys[nspace] = index++;
}
});
}
mp(this.rawData, "");
}
Storage.prototype.get = function(key){
return this.data[this.keys[key]];
};
Storage.prototype.data = [];
Storage.prototype.keys = {};
var store = new Storage(data);
console.log(data);
store.init();
console.log("keys", store.keys);
console.log("data", store.data);
console.log("kay1=", store.get(".kay1"));
console.log("key2=", store.get(".key2"));
console.log("key3.key31=", store.get("key3.key31"));
console.log("key3.key32=",store.get("key3.key32"));
console.log("key3.key33=", store.get("key3.key33"));

How does Javascript evaluate the right parenthesis?

I'm working on a calculator that takes an expression such as (5+4) and evaluates it by passing the buttons pressed to an array, and then building a parse tree from the data in the array.
What's interesting/strange, is that my code won't push the value of the right parenthesis to the array. Here is my code, could someone help me out?
The console.log activeButton shows that is the value of the button being pressed, but even when I placed calcArray.push() outside the if statements it would not push ) to an array.
$(document).ready(function(){
var calcArray = new Array();
$("input").click(function(){
var activeButton = this.value;
console.log(activeButton);
if(!isNaN(activeButton))
{
calcArray.push(parseInt(activeButton));
console.log(calcArray);
}
else if(activeButton === "=")
{
evaluate(buildTree(calcArray));
calcArray = [];
}
else
{
calcArray.push(activeButton);
}
});
});
The BuildTree code:
function BinaryTree(root) {
this.root = root;
this.activeNode = root;
}
function Node(element){
this.element = element;
this.parent;
this.rightChild;
this.leftChild;
this.setLeft = function(node){
this.leftChild = node;
node.parent = this;
};
this.setRight = function(node){
this.rightChild = node;
node.parent = this;
};
}
//methods
var buildTree = function(array)
{
var tree = new BinaryTree(new Node(null));
for(var i = 0; i < array.length; i++)
{
var newNode = new Node(array[i]);
if(array[i] == "(")
{
newNode.element = null;
tree.activeNode.setLeft(newNode);
tree.activeNode = newNode;
}
else if(array[i] == "+" || array[i] == "-" || array[i] == "/" || array[i] == "*")
{
tree.activeNode.element = newNode.element;
tree.activeNode.setRight(new Node(null));
tree.activeNode = tree.activeNode.rightChild;
}
else if(array[i] == ")")
{
if(tree.activeNode.parent == null)
{
;
}
else
{
tree.activeNode = tree.activeNode.parent;
tree.root = tree.activeNode;
}
}
else
{
tree.activeNode.element = newNode.element;
tree.activeNode = tree.activeNode.parent;
}
}
return tree.activeNode;
}
var evaluate = function(node){
var newNode1, newNode2;
newNode1 = new Node(null);
newNode1.parent = node;
newNode2 = new Node(null);
newNode2.parent = node;
if(node.leftChild == null && node.rightChild == null)
return node.element;
else{
newNode1.element = evaluate(node.leftChild);
newNode2.element = evaluate(node.rightChild);
if(newNode1.parent.element == "+")
{
return Number(newNode1.element) + Number(newNode2.element);
}
if(newNode1.parent.element == "-")
{
return newNode1.element - newNode2.element;
}
if(newNode1.parent.element == "*")
{
return newNode1.element * newNode2.element;
}
else
{
return newNode1.element / newNode2.element;
}
}
};

I just tried this out using your code and it worked fine passing the value as a string:
function pushButton (value) {
var activeButton = value;
console.log(activeButton);
if(!isNaN(activeButton))
{
calcArray.push(parseInt(activeButton));
console.log(calcArray);
}
else if(activeButton === "=")
{
evaluate(buildTree(calcArray));
calcArray = [];
}
else
{
calcArray.push(activeButton);
}
};
You aren't ever printing out the array in the last case (which is where the right paren would go), so are you sure it's not on the array and you just aren't seeing the visual feedback?
If so, we need to see more of your code. Try and setup a jsfiddle.