September 1, 2020

Formatting numbers with a fixed number of decimal places in JavaScript

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To format a number with a specified number of decimal places in JavaScript, use the toFixed() method.

Number.prototype.toFixed() - JavaScript | MDN

const number = 12.3456789; 
console.log(number.toFixed()) // 12 : Returns an approximation; without an argument, decimal places are set to 0.
console.log(number.toFixed(2)) // 12.35 : Returns an approximation

Personally, I often use this when displaying processing time during performance measurement.

const start = performance.now();
// some process
const end = performance.now();

const seconds = ((end - start) / 1000).toFixed(2);
console.log('Processing time: ', seconds, 's');  // 1.23s