Symec Engineers India Interview Questions and Answers

promise.all waits for all promises to resolve, while promise.race waits for the first promise to resolve or reject

• promise.all resolves when all promises in the iterable have resolved

• promise.race resolves or rejects as soon as one of the promises in the iterable resolves or rejects

• Example: Promise.all([promise1, promise2, promise3]) will wait for all three promises to resolve before resolving itself

• Example: Promise.race([promise1, promise2, promise3]) will resolve or reject as...read more

Use recursion to get unique keys in nested object

• Create a function that takes in an object as input

• Use recursion to iterate through the object and store unique keys in a Set

• Return an array of unique keys from the Set

Semantic HTML is using HTML elements that convey meaning to both the browser and the developer.

• Semantic HTML helps improve accessibility and SEO.

• Examples include using <header>, <nav>, <main>, <article>, <section>, <footer> tags instead of <div> for better structure and meaning.

• Semantic HTML makes it easier for developers to understand the structure of a webpage.

Debouncing in Javascript is a technique used to limit the number of times a function is called, typically used for handling events like scroll or resize.

• Debouncing involves setting a delay before a function is executed after the last time it was called.

• It helps in optimizing performance by preventing unnecessary function calls, especially for events that trigger frequently.

• Example: Implementing a debounce function for handling scroll events to improve performance.

Caching is a technique used to store copies of frequently accessed data in order to speed up retrieval times.

• Caching helps reduce the load on servers by serving cached content instead of generating it from scratch.

• Common types of caching include browser caching, server-side caching, and CDN caching.

• Examples of caching libraries/tools include Redis, Memcached, and Varnish.

• Cache invalidation is an important aspect of caching to ensure that stale data is not served to users.

Database design for a website similar to opx

• Identify the entities and their relationships (e.g. users, products, orders)

• Design tables for each entity with appropriate attributes

• Establish primary and foreign key relationships between tables

• Consider normalization to reduce redundancy and improve data integrity

• Implement indexes for efficient data retrieval

Projects are handled through effective planning, delegation, communication, and monitoring.

• Effective planning is crucial to set clear goals and timelines.

• Delegation of tasks based on team members' strengths and expertise.

• Regular communication to ensure everyone is on the same page.

• Monitoring progress and making adjustments as needed.

• Example: Using project management software to track tasks and deadlines.

A polyfill is a piece of code that provides the technology that you expect the browser to provide natively.

• Polyfill for promises can be used to add support for promises in older browsers that do not natively support them.

• Popular polyfills for promises include 'es6-promise' and 'bluebird'.

• Polyfills can be included in your project using a script tag or through a package manager like npm.