Troppus Web Solutions PHP Developer Interview Questions and Answers for Experienced

Q1. What is singleton class
Ans. 
A singleton class is a class that can only have one instance created throughout the application.
• Singleton classes are often used for logging, caching, database connections, and thread pools.

• They have a private constructor to prevent multiple instances from being created.

• The class typically provides a static method to access the single instance.
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Q2. What is Method reference
Ans. 
Method reference is a shorthand syntax for lambda expressions to call a method.
• Method reference is used to refer to a method without invoking it.

• It can be used to make code more concise and readable.

• There are four types of method references: static, instance, constructor, and array constructor.
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Q1. Javascipt question
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Q2. Promises, filter, map, What is single page , mulitple page application, opened google page by search for one product in that using console filter it only for sony products only
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Q3. What is DOM, what is the use of that
Ans. 
DOM stands for Document Object Model, it is a programming interface for web documents. It represents the structure of a document as a tree of objects.
• DOM is used to interact with HTML and XML documents in a structured way

• It allows developers to manipulate the content, structure, and style of a website dynamically

• DOM provides methods and properties to access and modify elements on a web page

• Example: document.getElementB...read more
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Q4. What is the output if u type document in console
Ans. 
The output will display the document object in the console.
• Typing 'document' in the console will return the document object, which represents the current HTML document.

• The document object provides access to the content and structure of the webpage, allowing manipulation of elements and properties.
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Q1. How to insert multiple values in one go
Ans. 
Use the INSERT INTO statement with multiple value sets separated by commas
• Use the INSERT INTO statement followed by the table name

• List the column names in parentheses after the table name

• Use the VALUES keyword followed by multiple value sets in parentheses, separated by commas

• Example: INSERT INTO table_name (column1, column2) VALUES (value1, value2), (value3, value4)
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Q2. Update query using joins
Ans. 
Update query using joins in SQL
• Use UPDATE statement with JOIN clause to update data in multiple tables

• Specify the tables to be updated and joined using ON clause

• Set the columns to be updated in SET clause
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Q1. What is closures in JS ?
Ans. 
Closures in JavaScript are functions that have access to variables from their outer scope, even after the outer function has finished executing.
• Closures are created when a function is defined inside another function.

• The inner function has access to the outer function's variables, parameters, and even the outer function's return value.

• Closures are useful for creating private variables and data encapsulation.

• They can be ...read more
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Q2. Diff props and state ?
Ans. 
Props and state are both used in React to manage and pass data, but they have different purposes and behaviors.
• Props are read-only and passed from parent components to child components.

• State is mutable and managed within a component.

• Props are used to pass data from a parent component to a child component.

• State is used to manage and update data within a component.

• Props are passed as attributes to a component in JSX.

• Stat...read more
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Q3. How to optimise the performance ?
Ans. 
Performance optimization involves identifying and resolving bottlenecks to improve the efficiency of software.
• Identify and analyze performance bottlenecks

• Optimize algorithms and data structures

• Improve database performance through indexing and query optimization

• Use caching techniques to reduce database and network calls

• Minimize network latency by optimizing network requests

• Optimize front-end code by reducing DOM manipul...read more
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Q4. Diff between class based or function based component ?
Ans. 
Class-based components are ES6 classes that extend React.Component, while function-based components are functions that return JSX.
• Class-based components are more feature-rich and have access to lifecycle methods.

• Function-based components are simpler and easier to read and test.

• Class-based components can have state and use lifecycle methods like componentDidMount and componentDidUpdate.

• Function-based components can use ...read more
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Q5. What is es6 features ?
Ans. 
ES6 (ECMAScript 2015) introduced several new features to JavaScript, enhancing its functionality and making it more efficient.
• Arrow functions: concise syntax for writing functions

• Let and const: block-scoped variables

• Template literals: easier string interpolation

• Destructuring assignment: extracting values from arrays or objects

• Spread syntax: expanding elements in arrays or objects

• Classes: syntactical sugar for creating ...read more
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Q1. Explain oops concepts
Ans. 
Object-oriented programming concepts like inheritance, encapsulation, polymorphism, and abstraction.
• Inheritance: Allows a class to inherit properties and behavior from another class.

• Encapsulation: Bundling data and methods that operate on the data into a single unit.

• Polymorphism: Ability to present the same interface for different data types.

• Abstraction: Hiding the complex implementation details and showing only the ne
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Q2. Explain solid principles
Ans. 
SOLID principles are a set of five design principles that help developers create more maintainable and scalable software.
• Single Responsibility Principle (SRP) - A class should have only one reason to change.

• Open/Closed Principle (OCP) - Software entities should be open for extension but closed for modification.

• Liskov Substitution Principle (LSP) - Objects of a superclass should be replaceable with objects of its subcla...read more
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Q1. They asked Oops concepts
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Q2. They asked exception handling
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Q1. Tell me about yourself
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Moderate to difficult

Q1. DSA questions based on Dynamic programming
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