Synchronous code runs in sequence. This means that each operation must wait for the previous one to complete before executing.
console.log('One');
console.log('Two');
console.log('Three');
// LOGS: 'One', 'Two', 'Three'Asynchronous code runs in parallel. This means that an operation can occur while another one is still being processed.
console.log('One');
setTimeout(() => console.log('Two'), 100);
console.log('Three');
// LOGS: 'One', 'Three', 'Two'Asynchronous code execution is often preferable in situations where execution can be blocked indefinitely. Some examples of this are network requests, long-running calculations, file system operations etc. Using asynchronous code in the browser ensures the page remains responsive and the user experience is mostly unaffected.
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JavaScript Interview Questions
Snippet collection
Prepare for your next JavaScript interview with this collection of interview questions and answers.
Pipe async functions
JavaScript, Function
Performs left-to-right function composition for asynchronous functions.
Delay async function execution
JavaScript, Function
Delays the execution of an asynchronous function.
Promisify function
JavaScript, Function
Converts an asynchronous function to return a promise.