Determining the occurrence of a specific value within an array using JavaScript

Question

Determining the occurrence of a specific value within an array using JavaScript

Can you help refine my function? I've created one that counts the number of 7s in an array, but it only counts each element once even if it has multiple 7s. How can I modify it to calculate the total number of 7s in the array without missing any? Please explain the solution in an easy-to-understand manner since I am new to JavaScript.

function sevenBoom(arr){
  debugger;
  let singleElement, string, includeSeven;
  let flag = false;
  let counter = 0;

  for (let i=0; i<arr.length; i++){
    singleElement = arr[i];
    string = singleElement.toString();
    includeSeven = string.includes("7");
    if (includeSeven == true){
      flag = true;
      counter += 1;    
    }   
  }
  if (counter == 0){
    return "There is no 7 in the array";
  }else{
    return `Boom! There are ${counter} 7s in the array...`;
  }
}
arr = [6,7,87, 777, 107777];
sevenBoom(arr);

javascript arrays

Answer 1

Answer №1

Transform an array of numeric values into an array of single-character strings:

/**
* @param {string} char - enclose the number you want to find in quotes
* @array {array<number>} array - an array of numbers
*/
function convertToChar(char, array) {...

/*
.string() converts each number to a string
.map() returns those strings as an array of strings
.join('') merges that array of strings into a single string
.split('') then splits that single string and produces an array containing single character strings.
*/
const chars = array.map(num => num.toString()).join('').split('')

Afterwards, filter the array of characters based on a specified number ('7') and return the count:

// Selects only characters that match the given character ('7')
const hits = chars.filter(str => str === char);
return hits.length;

const seven = [0, 100.7, 8, 9, 55, -63, 7, 99, -57, 777];

function convertToChar(char, array) {
  const chars = array.map(num => num.toString()).join('').split('');
  const hits = chars.filter(str => str === char);
  return hits.length;
}

console.log(convertToChar('7', seven));

Answer 2

Transform an array of numeric values into an array of single-character strings:

/**
* @param {string} char - enclose the number you want to find in quotes
* @array {array<number>} array - an array of numbers
*/
function convertToChar(char, array) {...

/*
.string() converts each number to a string
.map() returns those strings as an array of strings
.join('') merges that array of strings into a single string
.split('') then splits that single string and produces an array containing single character strings.
*/
const chars = array.map(num => num.toString()).join('').split('')

Afterwards, filter the array of characters based on a specified number ('7') and return the count:

// Selects only characters that match the given character ('7')
const hits = chars.filter(str => str === char);
return hits.length;

const seven = [0, 100.7, 8, 9, 55, -63, 7, 99, -57, 777];

function convertToChar(char, array) {
  const chars = array.map(num => num.toString()).join('').split('');
  const hits = chars.filter(str => str === char);
  return hits.length;
}

console.log(convertToChar('7', seven));

Answer 3

Answer №2

When dealing with your data

const numbers = [6,7,87, 777, 107777];

If you want to find the occurrences of the number 7 in the array, you can utilize reduce and split in this manner

const countNumbers = numbers.map((num) => {
  return num
    .toString()
    .split("")
    .reduce((acc, current) => (current === "7" ? acc + 1 : acc), 0);
});

The resulting array from the above operation would be

[0, 1, 1, 3, 4]

This means that for the original array [6,7,87, 777, 107777], we obtain [0, 1, 1, 3, 4]

Check out the CodeSandbox link for a hands-on example: https://codesandbox.io/s/lucid-keldysh-9meo3j?file=/src/index.js:38-186

Answer 4

When dealing with your data

const numbers = [6,7,87, 777, 107777];

If you want to find the occurrences of the number 7 in the array, you can utilize reduce and split in this manner

const countNumbers = numbers.map((num) => {
  return num
    .toString()
    .split("")
    .reduce((acc, current) => (current === "7" ? acc + 1 : acc), 0);
});

The resulting array from the above operation would be

[0, 1, 1, 3, 4]

This means that for the original array [6,7,87, 777, 107777], we obtain [0, 1, 1, 3, 4]

Check out the CodeSandbox link for a hands-on example: https://codesandbox.io/s/lucid-keldysh-9meo3j?file=/src/index.js:38-186

Answer 5

Answer №3

The function has been updated to tally the occurrences of the numeral "7" in each number within the Array.

A Regex pattern, /7/g, is utilized to count the instances of 7 in every string element. For a detailed explanation of this regex, click here.

Within the loop, it tallies how many times "7" appears in each array element and calculates the cumulative total accordingly.

Fiddle in Action

function sevenBoom(arr) {
    let singleElement, string, includeSeven;
    let flag = false;
    let counter = 0;

    for (let i = 0; i < arr.length; i++) {
        singleElement = arr[i];
        string = singleElement.toString();
        const count = (string.match(/7/g) || []).length;
        if (count > 0) {
            flag = true;
            counter += count;
        }
    }
    if (counter == 0) {
        return "There is no 7 in the array";
    } else {
        return `Boom! There are ${counter} 7s in the array...`;
    }
}
arr = [6, 7, 87, 777, 107777];
console.log(sevenBoom(arr));

Answer 6

The function has been updated to tally the occurrences of the numeral "7" in each number within the Array.

A Regex pattern, /7/g, is utilized to count the instances of 7 in every string element. For a detailed explanation of this regex, click here.

Within the loop, it tallies how many times "7" appears in each array element and calculates the cumulative total accordingly.

Fiddle in Action

function sevenBoom(arr) {
    let singleElement, string, includeSeven;
    let flag = false;
    let counter = 0;

    for (let i = 0; i < arr.length; i++) {
        singleElement = arr[i];
        string = singleElement.toString();
        const count = (string.match(/7/g) || []).length;
        if (count > 0) {
            flag = true;
            counter += count;
        }
    }
    if (counter == 0) {
        return "There is no 7 in the array";
    } else {
        return `Boom! There are ${counter} 7s in the array...`;
    }
}
arr = [6, 7, 87, 777, 107777];
console.log(sevenBoom(arr));

Determining the occurrence of a specific value within an array using JavaScript

Answer №1

Answer №2

Answer №3

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