JavaScript: Round a number to a specified amount of digits

JavaScript fundamental (ES6 Syntax): Exercise-152 with Solution

Round Number to Digits

Write a JavaScript program to round a number to a specified amount of digits.

• Use Math.round() and template literals to round the number to the specified number of digits.
• Omit the second argument, decimals, to round to an integer.

Sample Solution:

JavaScript Code:

//#Source https://bit.ly/2neWfJ2 
// Define a function 'round' that rounds a number 'n' to the specified number of 'decimals'
const round = (n, decimals = 0) => 
  // Convert 'n' to a string in scientific notation with the desired number of decimals
  Number(`${Math.round(`${n}e${decimals}`)}e-${decimals}`);

// Test the 'round' function with different inputs
console.log(round(1.005, 2)); // Output: 1.01
console.log(round(1.05, 2));  // Output: 1.05
console.log(round(1.0005, 2)); // Output: 1

Output:

1.01
1.05
1

Visual Presentation:

Flowchart:

Live Demo:

See the Pen javascript-basic-exercise-152-1 by w3resource (@w3resource) on CodePen.

For more Practice: Solve these Related Problems:

• Write a JavaScript program that rounds a number to a specified number of decimal places using exponential notation.
• Write a JavaScript function that implements bankers’ rounding to round a number to n digits.
• Write a JavaScript program that rounds a large floating-point number accurately without using toFixed().
• Write a JavaScript program that rounds numbers in an array to varying digit precisions provided by a mapping function.

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