Frontend Developer Team Lead Interview Questions and Answers

In JavaScript, '==' checks for value equality, while '===' checks for both value and type equality.

• '==' performs type coercion, converting operands to the same type before comparison.

• Example: '5' == 5 evaluates to true because '5' is coerced to a number.

• '===' checks both value and type, so no coercion occurs.

• Example: '5' === 5 evaluates to false because one is a string and the other is a number.

• Use '==' when you want to allow type conversion; use '===' for strict comparisons ...read more

I ensure web accessibility by following WCAG guidelines, conducting audits, and implementing best practices for inclusive design.

• Conduct accessibility audits using tools like Axe or Lighthouse to identify issues.

• Implement semantic HTML elements (e.g., <header>, <nav>, <main>, <footer>) for better screen reader support.

• Ensure color contrast ratios meet WCAG standards (e.g., 4.5:1 for normal text).

• Use ARIA roles and attributes to enhance accessibility for dynamic content.

• Provid...read more

Effective state management in large-scale frontend apps involves structured approaches, tools, and best practices for maintainability.

• Use a centralized state management library like Redux or MobX to manage application state consistently.

• Implement local component state for UI-specific data to avoid unnecessary global state updates.

• Utilize React's Context API for passing down state without prop drilling in deeply nested components.

• Adopt a modular architecture by splitting state...read more

call, apply, bind set function context; async functions handle asynchronous operations in JavaScript.

• call: Invokes a function with a specified 'this' value and arguments. Example: func.call(obj, arg1, arg2);

• apply: Similar to call, but takes an array of arguments. Example: func.apply(obj, [arg1, arg2]);

• bind: Returns a new function with a specified 'this' value, allowing for partial application. Example: const boundFunc = func.bind(obj, arg1);

• Asynchronous functions: Use 'async'...read more

React lifecycle methods manage component behavior during its lifecycle phases: mounting, updating, and unmounting.

• componentDidMount: Invoked immediately after a component is mounted. Ideal for API calls. Example: fetchData() in componentDidMount().

• componentDidUpdate: Invoked immediately after updating occurs. Useful for responding to prop or state changes. Example: if (prevProps.id !== this.props.id) { fetchData(); }

• componentWillUnmount: Invoked immediately before a component...read more

Controlled components manage form data via state, while uncontrolled components rely on the DOM for data handling.

• Controlled components use React state to manage input values. Example: <input value={this.state.value} onChange={this.handleChange} />.

• Uncontrolled components store their own state internally. Example: <input defaultValue='initial' ref={input => this.input = input} />.

• In controlled components, form data is handled by React, making it easier to validate and manipul...read more