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Eugeniu Cozac @prince86

Senior Front End Developer

Hashing

Algorithms

It is an efficient searching technique. Searching is a widespread operation on any data structure. Hashing is used to search specific records from a large domain of records. If we can efficiently search a record out of  many records, we easily perform different operations on that data. Hashing is storing and retrieving data from the database in the order of O(1) time. We can also call it the mapping technique because we try to map smaller values into larger values by using hashing.

Following are the significant terminologies related to hashing

Search Key

In the database, we usually perform searching with the help of some keys. These keys are called search keys. If we take the student data, then we search by some registration number. This registration number is a search key. We have to put the search keys in hash tables.

Hash Table

It is a data structure that provides us the methodology to store data properly. A hash table is shown below. It is similar to an array. And we have indexes in it also like an array.

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Binary Search

Algorithms

Searching is the method to search for a specific element in a group of an element. It needs a unique identity that is associated with the desired element. As a unique identity of that desired element has been found, the index to that desired element is returned.  The index indicates the location or address where that specific element has been found in the list elements of the array. If the desired data is found, particular data has been returned. Otherwise, it returned a null value.

There are several categories of search algorithms such as.

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Total votes 3: ↑2 and ↓1 +1
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Diving Into Angular Services

Angular

When building any kind of application, it is often seen that a certain functionality is needed again and again at different points. It could be the functionality to display something in a certain way or retrieve data from a source, to name a few examples. Such a common case like this can appear in all kinds of development, be it front-end or back-end. A robust front-end development framework like Angular handles such a case by allowing the development of objects that can be imported by any part as needed. These objects can extract some common logic or data are known as services.

This article helps you understand what Angular services are and what are the different kinds of use-cases they can be used in. Angular services are not limited to one particular type of job and can contain methods that are repeatedly required by different components of the application. Afterward, this article will show what it is like to code service and what makes it accessible to any of the components.

The Gist Of What Angular Services Are

Given how fundamental components are to Angular applications, it is important to briefly go through them to further understand any other concept, like services. Apart from that, components and services are often confused with each other as well. Hence, it is necessary to refresh our understanding of components.

Components are the very backbone of Angular applications. All the different functionalities or visual elements of the application are attributed to a component. Every component contains the working logic for the functionality or visual element and the instructions for its visual rendering. Every Angular application is based on a tree of components. In the component tree, every component working is dependent on or consists of, other component(s).

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Total votes 4: ↑3 and ↓1 +2
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A Quick Guide To Angular Pipes

Angular

Impressive web development is the result of a successful synergy of robust back-end and an appealing front-end. Usually, the back-end is thought to be the ‘brains’ of a webpage and the front-end is merely the shiny exterior. However, with the right front-end development framework, powerful computations can happen directly on the front-end as well. Angular happens to be one of such impressive front-end development frameworks. Through its templates, Angular offers the opportunity for data to be processed and formatted in a certain way right there in the HTML code. This is made possible through functions with easy-to-understand syntax and usage, and they are called pipes.

This article will serve as a quick guide to tell you all the meaty stuff to know about pipes and how to effectively use them. Pipes come in various types and can significantly simplify data collection and processing in use cases where the front-end is the main gateway of obtaining the data. The article will also discuss how pipes are tested during the unit testing of Angular applications (which is not as difficult as it may seem for some).

The Ins And Outs Of Angular Pipes

Before moving on to discussing Angular pipes, it is imperative to understand what Angular components and templates are. Pipes are present in the template part of the component, making it necessary to understand the former to grasp the utility of the latter.

Angular applications are fundamentally made up of units called components. Each component is centered around a certain functionality or visual aspect of the application. These components are self-contained and consist of both its working logic along with instructions about its visual rendering. The latter is stored in what are called templates. Templates are simply HTML code that can be in the form of a separate file or inline code within the @Component decorator (which is written in TypeScript). An example of an Angular component can be seen below.

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Knowing All About Angular Templates

Angular

All the popular frameworks used in the world of front-end development have different approaches to the tools offered for development. However, almost all frameworks focus on providing as much encapsulation as possible. More encapsulation would mean that the developer does not need to worry about nitty-gritty details and the client does not see what they don’t need to see. This leads to a smoother development and an easy-to-understand view of the application to the client. The popular front-end development framework Angular exhibits this principle in many different ways. One of the most prominent examples being through the use of templates.

This article explains what templates are and how Angular uses them to further streamline the front-end development process. Through templates, a developer is able to keep the graphical layout of an aspect of the Angular application separate from its working logic. However, communication between the graphical and logical parts is still possible. This article will take you through to make use of these templates and some of the more advanced functionality they can offer.

Understanding Angular Templates

Before moving on to discussing templates, it is important to grasp what Angular components are. After all, a template is an integral part of a component. Through components, we will be able to better understand the purpose and workings of a template.

At the fundamental level of any Angular application lies a tree of components. Each bigger component is connected to a child component(s) that it can pass data on to and invoke the creation of. Each component is associated with a certain functionality of the application and this modular nature helps with a more sophisticated development process. The Angular component is self-contained, in the sense that it consists of the working logic for the functionality and its visual representation. While the former is defined through a class, the latter is done through a template.

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Dictionary/Map

Algorithms

A basic data structure in computer science is the “associative array” known as a “map”. This structure is called a “dictionary”. Dictionaries are being used when you have key-value pairs of the information. Inputs are called keys, and outputs are called values. A dictionary is the abstract data type that can store elements so that they can be positioned quickly by using keys. Dictionary is like a container that will have a searchable assortment of items. Each item in the dictionary is stored as a key-value pair. In a dictionary, we can store multiple items with the same key.

Dictionary consists of multiple elements in terms of key and value pair. Both key and value are considered as one single pair. This is called mapping. Elements of the dictionary are enclosed in curly brackets in terms of key and value pairs. Dictionaries enable us to work with key-value pairs. Key-value pairs are two linked values where the key is the unique identifier where we can discover our data and the value is that the information.

Dictionary maps key-value pairs. It is a collection data type that has key-value pairs. A dictionary does not contain any duplicate members.

It is unordered and stores data values like a map. Thus, it is similar to the real-life dictionary with distinct key values. In a dictionary, we use keys as indexes to access elements.

The dictionary helps us to organize the collection of data. It is a special data type. Its syntax is:

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Getting To Know Angular Components

Angular

Angular is one of the most popular front-end development frameworks out there. It is a leading choice for personal as well as industry-level development of web applications due to its robust capabilities. While Angular is popular for many different reasons, one of the main ones is its modular nature. Modularity makes it easy for the developer to keep track of all the different elements being used to program functionalities. It also helps in keeping consistency and even reusing a block of code or functionality multiple times.

This modularity lies at the heart of Angular in the form of elements called components. This article will quickly take you through all the important bits to know about Angular components, their usage, how they are useful, and some code examples. Components make Angular easy to learn and applications easy to structure. Through this article, you’ll get to see how Angular components make all of this possible.

What Are Angular Components Exactly?

Components lie at the foundation of Angular applications. They interact similar to how HTML elements do in terms of passing data between elements and emitting events. Each of the components has some behavior attached to it that tells what data to render or load and a template that tells it how to render the data. An Angular application is based on a component tree structure where different components have child components and so on. Data is shared from parent to child components through an ‘input binding.’ Similarly, it can be shared the other way around through outputs.

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Binary Tree

Algorithms

Data structures are classified into linear and non-linear data structures. A tree is a non-linear data structure. Data is stored hierarchically in a non-linear data structure. So the tree is a way of organizing data hierarchically. A tree grows from top to bottom. In a tree, there are different kinds of nodes that are linked with each other. A tree consists of the following elements:

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Total votes 3: ↑2 and ↓1 +1
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Graph

Algorithms

It is a collection of edges and vertices. It can be used to display any form of network.

The following graph contains a total of 4 vertices and 5 edges. In this graph, vertices are A, B, C and D while edges are AB, BD, DC, CA and AD. Vertices are also known as nodes. The line connecting these vertices is the edge. Vertices are like objects and edges indicate the relation between those vertices. Data is stored in nodes. This data can be of numerical data type or any other data structure.

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Total votes 4: ↑3 and ↓1 +2
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Recursion

Algorithms

Recursion is a strategy that algorithms use to solve specific problems. A recursive algorithm is an algorithm that solves the main problem by using the solution of a simpler sub-problem of the same type. Recursion is a particular way of solving a problem by having a function calling itself repeatedly. It is always applied to a function only. By using recursion, we can reduce the size of the program or source code. In recursion, a function invokes itself. And the function that invokes itself is referred to as a recursive function.

Suppose we have a user-defined function named ‘recursion’, and it will be written in the main function. The compiler will execute the recursion function automatically, and it will search for a particular function definition. This function definition will be executed, and control will go back to the main function. If we call the same function inside the function definition, then the compiler will move on to function definition first. When the compiler executes the recursion function, we will be calling the same function.

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Memoization

Algorithms

Dynamic programming is applied to solve optimization problems. In optimization, we try to find out the maximum or minimum solution of something. It will find out the optimal solution to any problem if that solution exists. If the solution does not exist, dynamic programming is not able to get the optimal solution.

Optimization problems are the ones that require either lowest or highest possible results. We attempt to discover all the possible solutions in dynamic programming and then choose the best optimal solution. Dynamic programming problems are solved by utilizing the recursive formulas though we will not use a recursion of programming the procedures are recursive. Dynamic programming pursues the rule of optimality. 

A dynamic programming working involves around following significant steps:

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Total votes 3: ↑3 and ↓0 +3
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Big O Notation

Algorithms

Asymptotic notations are used to represent the complexity or running time of an algorithm. It is a technique of defining the upper and lower limits of the run-time performance of an algorithm.  We can analyze the runtime performance of an algorithm with the help of asymptotic notations. Asymptotic notations are also used to describe the approximate running time of an algorithm.

Types of Asymptotic Notations

Following are the different types of asymptotic notations:

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Breadth/Depth First Search

C++

A graph is a kind of data structure that includes a set of vertices and edges. Graph traversing means a visit to each vertex of the graph precisely. The graph traversing is used to determine the order in which vertices are being visited throughout the search process. A graph traversing searches for the edges that will be used in the search operation without establishing loops. This means that using graph traversal, we will go to all the vertices of the graph without going into a looping path.

There are two kinds of graph traversal methods.

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Stack And Queue

C++

Stack

Stack is a linear data structure. In stack, data access is limited. It follows the rule of insertion and deletion of data. Stack is a collection of only similar data types. Elements in the stack are arranged sequentially. It follows the LIFO principle which is the last-in and first-out rule.

Example

To understand this concept, let us take an example of arranging coins. If we start placing coins one after the other in such a way that the first coin will be placed first at the bottom and the next coin will come on above the first coin and so on. Now if we want to remove coins, then the topmost coin which is the third coin will be removed first. So in this way, the last coin will be removed first according to the LIFO principle.

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Total votes 2: ↑2 and ↓0 +2
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Валидация в HTML5

HTML
Recovery mode
Интерактивные веб-сайты и приложения невозможно представить без форм, которые позволяют нам общаться с нашими пользователями и получать данные, необходимые для обеспечения гладких сделок с ними. В то время как мы можем улучшить удобство и простоту использования наших форм с удачно выбранным шаблоном проектирования UX. HTML5 также имеет собственный механизм для ограничения проверки, который позволяет нам поймать ошибки ввода прямо на фронт энде.

Проверка ввода имеет основную цель — безопасность. Когда речь идет о безопасности, это означает, что мы должны предотвратить инъекции вредоносного контента — будь то преднамеренные или случайные.При проверке внешнего интерфейса ввода, наша работа состоит в том, чтобы установить разумные ограничения на ввод данных пользователем.

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Total votes 17: ↑11 and ↓6 +5
Views27.9K
Comments 6

Альтернатива Themeforest для тех, кто хочет продавать темы на WordPress

CMS

Я давно верстаю и делаю темы для WordPress: где-то уже более 4 лет. И, когда через года два после начала, я сделал больше 100 сайтов на WordPress, то конечно пришла мысль о том, как сделать себе пассивный заработок на создании плагинов и тем для Envato и ThemeForest. Поначалу впечатлила самая продаваемая тема Avada и, конечно же, плагины Revolution Slider и Visual Composer. Сразу начинаешь умножать продажи на цену и получается прилично. Первое время я даже не замечал темы на WordPress, которые имели очень хороший дизайн, но при этом у них почти не было продаж. Можете даже посмотреть один пример: здесь и дизайн крутой и функционал неплохой, но продаж только 20 за 4 месяца.


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Total votes 14: ↑8 and ↓6 +2
Views11.3K
Comments 12

Знакомство с p5.js

JavaScript
Recovery mode

Я уже более 5 лет являюсь фронт енд разработчиком и всегда пытаюсь быть в курсе всех новостей. Помню что два года назад я заинтересовался графикой в JavaScript. И тут за пару месяцев я начал делать исследование про графику в JavaScript, так как у меня был тогда проект на D3.js. Во первых я начал изучать Canvas и SVG что является частью HTML5 но тоже нужно писать код в JS, например у меня проект был кустомизировать дорогие часы на Canvas. Следующий проект с графикой был с D3.js он был довольно прост, там нужно было на базе данных всех продаж компании показать графики в D3.js. Последний мои проект на базе гафики будет на p5.js и я решил узнать всё про него, и в этой публикации я хочу поделится своим исследованием про этот p5.js.


P5.js был создан командой Processing в 2014 году. Это JavaScript библиотека, с особым акцентом на изобразительное искусство. Цель P5.js совпадает с изначальной целью Processing — это снизить порог входа в программирование для художников, дизайнеров, учителей. С P5.js можно легко создавать бесконечно большое количество вариантов отображения информации: от веб-формата, статичных картинок для печати, до анимированных и интерактивных схем.


Processing был создан в 2001 году с целью обучить программированию непрограммистов, но с тех пор он стал основным языком для десятков тысяч художников и дизайнеров. P5.js делает рендеринг файлов PDE с исходным кодом Processing. При использовании этой библиотеки программист может вообще не знать JavaScript. Детально об отличиях Processing и p5 можно почитать в этой статье.


Для рендеринга используется canvas, а также p5.js поддерживает работу со звуком и видео. P5.js включает в себя совокупность обьектов, функций, констант с помощью которых можно создавать произвольные формы. Весь ряд возможностей p5.js можно найти в справочнике на официальном сайте.

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Total votes 25: ↑25 and ↓0 +25
Views26.5K
Comments 13

20+ Моих любимых AngularJS помощников

JavaScriptAngular
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В этой статье я решил собрать более чем 20 AngularJS инструментов, которые ежедневно облегчают мой процесс разработки на AngularJS вот уже на протяжении нескольких лет. Когда я перешел с чистого JavaScript на AngularJS, я хотел быть в курсе всех новинок AngularJS и для этого я сделал исследование. Для меня было очень важно быть на правильном пути. По моему опыту когда ты знаешь и пользуешься всеми новинками то освоение этого JS фреймворка идёт быстрее. После всего этого исследования на протяжении двух лет я успел попробовать следующие инструменты. Здесь вы найдете инструменты для тестирования, front-end разработки, IDE, текстовые редакторы, библиотеки, модули, расширения, генераторы кода, Grid-инструменты и другое.

Перейдем к списку.

В начале я бы хотел ознакомить вас с тремя, на мой взгляд, лучшими AngularJS инструментами для тестирования:

1. Karma

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Karma один из моих любимых AngularJS инструментов для тестирования. Он обеспечивает идеальную среду для тестирования, что позволяет протестировать приложение в реальных браузерах и реальных устройствах, таких как телефоны и планшеты.
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Total votes 38: ↑28 and ↓10 +18
Views24.8K
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Благовещенск (Амурская обл.), Амурская обл., Россия
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