Js How to got the sum of numbers from a string?

Question

I'm new to coding and have been given this question;

Create a function that takes a string with a jumble of letters and numbers. It should add together all the numbers that appear in the string and return the total.

   E.g. 'foo5bar6cat1' => 12
   'foo99cat' => 18

Tip: For this one, it might be useful to know that the value NaN in JavaScript behaves oddly. For example, if you do typeof NaN it tells you it's a "number". Odd, eh?

The code that I have written is this;

function sumDigitsFromString(str) {
let nums = []
let sum = 0

for (let i = 0; i < str.length; i++) {
if (typeOf (arr[i]) === "number") {
 nums.push(str[i])
    }
}
 for (let i = 0; i < nums.length; i++){
sum.push(nums[i] + sum)
   }
return sum
}

The test that my code is being run against is this;

describe("sumDigitsFromString", () => {
   it("picks out a digit from a string and returns", () => {
expect(sumDigitsFromString("foo5foo")).to.equal(5);
   });
     it("sums multiple digits from a string", () => {
expect(sumDigitsFromString("5foo5foo")).to.equal(10);
    });
it("returns a seum of several digits in a string", () => {
         expect(sumDigitsFromString("hello1world5this3is2a2string")).to.equal(13).;
   });
});

Dose anyone have any suggestion of how to fix my code?

Answer 1

function numberAdd(str){
	var strArr = str.split(""), strTemp=0;
	for(i=0;i<strArr.length;i++){
		if(!isNaN(strArr[i])){
			strTemp+=parseInt(strArr[i]);
		}
	}
	return strTemp;
}

var str = 'foo5bar6cat1';
console.log(numberAdd(str));

Answer 2

Your method won't work because of so many reasons, Try to change your method as following and it should do the trick,

function sumDigitsFromString(str) {
    var sum = 0;
    var numbers = str.match(/\d+/g).map(Number);
    for (var i = 0; i < numbers.length; i++) {
        sum += numbers[i]
    }
    return sum;
}

Answer 3

You're almost on the right track.

if (typeOf (arr[i]) === "number") {

I think you meant to use str[i] instead of arr[i]. arr was not defined earlier.

if (typeof(str[i]) === "number") {

This will always be false. Every str[i] is a string. Correct is using:

if (!isNaN(Number(str[i]))) {

where if str[i] is not a number, Number(str[i]) will return NaN.

nums.push(str[i])

You need to push numbers not strings. Use Number(str[i]).

sum.push(nums[i] + sum)

sum is of type Number. You can't push to a number. You need to add to that number. Use sum += nums[i] instead.

So the complete, working code will be:

function sumDigitsFromString(str) {
  let nums = [];
  let sum = 0;

  for (let i = 0; i < str.length; i++) {
    if (!isNaN(Number(str[i]))) {
      nums.push(Number(str[i]));
    }
  }
  console.log(nums);
  for (let i = 0; i < nums.length; i++) {
    sum += nums[i];
  }
  return sum;
}

// Test it
console.log(sumDigitsFromString("foo5bar6cat1"));

Answer 4

An alternative solution if you are solving for numbers as the combination of a series within a string (ie 'zz11yx33ab' -> 44) or ('020a010b030c11' -> 71).

let string = '020a010b030c11';

function sumNumbers(string) {
  let pos = 1;
  let numArray = [];
  let numString = null;

  for (let num of string) {
    let isParsed = isNaN(parseInt(num));
    if (!numString && !isParsed && pos === string.length) {
      numArray.push(num);
    } else if (!numString && !isParsed && pos !== string.length) {
      numString = num;
    } else if (numString && !isParsed && pos === string.length) {
      numString += num;
      numArray.push(numString);
    } else if (numString && isParsed && pos === string.length) {
      numArray.push(numString);
    } else if (numString && !isParsed) {
      numString += num;
    } else if (numString && isParsed && pos !== string.length) {
      numArray.push(numString);
      numString = null;
    } else if (!numString && isParsed && pos === string.length) {
      numString += num;
      numArray.push(numString);
    }
    pos++;
  }
  console.log('numAray:', numArray);
  let result = null;

  for (let num of numArray) {
    let value = parseInt(num);
    result += value;
  }
  return result;
}

let finalNum = sumNumbers(string);
console.log(finalNum);

Answer 5

• typeOf is supposed to be typeof. You don't want this in your code though because it will give all the elements in the string array a string value.

• Use parseInt() to make all the elements in the array numbers and then weed out the ones who return NaN with isNaN()

  function sumDigitsFromString(str) {
      let nums = []
      let sum = 0
  
      for (let i = 0; i < str.length; i++) {
          if (!isNaN(parseInt(str[i]))) {
              sum += parseInt(str[i])
          }
      }
      return sum
  }
  

Answer 6

let sum =0;
for(char of string)
    isNaN(parseInt(char)) ? sum=sum+0:sum=sum+parseInt(char);

this should serve the purpose....ES6 syntax used.

Answer 7

let test = 'naseef123hello66'

//declared an empty array
let nums = [];

//declared a sum variable  
let sum = 0;

//check whether it is number or alphabet 
for(i=0;i<test.length;i++){
 if (!isNaN((test[i]))) {
  nums.push(Number(test[i]));
 }
}

//itrating arr and find sum with basic arithmetic operation
for (k=0;k<nums.length;k++){
sum = sum + nums[k]
}

console.log("sum : "+sum)

let test = 'naseef123hello66'

//declared an empty array
let nums = [];

//declared a sum variable  
let sum = 0;

//check whether it is number or alphabet 
for(i=0;i<test.length;i++){
 if (!isNaN((test[i]))) {
  nums.push(Number(test[i]));
 }
}

//itrating arr and find sum with basic arithmetic operation
for (k=0;k<nums.length;k++){
sum = sum + nums[k]
}

console.log("sum : "+sum)