JavaScript: Insert dashes (-) between each two even digits of a specific number

Last update on March 03 2025 12:45:39 (UTC/GMT +8 hours)

JavaScript Array: Exercise-6 with Solution

Insert Dashes Between Evens

Write a JavaScript program that accepts a number as input and inserts dashes (-) between each even number. For example if you accept 025468 the output should be 0-254-6-8.

Sample Solution:

JavaScript Code:

// Prompt the user for input and store it in the 'num' variable
var num = window.prompt();

// Convert the number to a string and store it in the 'str' variable
var str = num.toString();

// Initialize an array 'result' with the first character of the string
var result = [str[0]];

// Iterate through the characters of the string starting from index 1
for (var x = 1; x < str.length; x++) {
  // Check if the previous and current characters are both even digits
  if (str[x - 1] % 2 === 0 && str[x] % 2 === 0) {
    // If both are even, push a '-' and the current character to the 'result' array
    result.push('-', str[x]);
  } else {
    // If not both even, push the current character to the 'result' array
    result.push(str[x]);
  }
}

// Output the joined 'result' array as a string
console.log(result.join(''));

Output:

0-254-6-8

Flowchart:

ES6 Version:

// Prompt the user for input and store it in the 'num' variable
const num = window.prompt();

// Convert the number to a string and store it in the 'str' variable
const str = num.toString();

// Initialize an array 'result' with the first character of the string
const result = [str[0]];

// Iterate through the characters of the string starting from index 1
for (let x = 1; x < str.length; x++) {
  // Check if the previous and current characters are both even digits
  if (str[x - 1] % 2 === 0 && str[x] % 2 === 0) {
    // If both are even, push a '-' and the current character to the 'result' array
    result.push('-', str[x]);
  } else {
    // If not both even, push the current character to the 'result' array
    result.push(str[x]);
  }
}

// Output the joined 'result' array as a string
console.log(result.join(''));

Live Demo:

For more Practice: Solve these Related Problems:

Write a JavaScript function that accepts a number as a string and inserts dashes between every two consecutive even digits.
Write a JavaScript function that processes a numeric string and correctly handles leading zeros when inserting dashes.
Write a JavaScript function that validates the input and returns the original string if no consecutive even digits exist.
Write a JavaScript function that implements dash insertion without converting the string into an array.

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