Declare a function ‘numCount’, which takes in a single number as an argument and returns another function. The returned function takes a string as an argument, and when invoked, it will search that string for the number initially passed in to the ‘numCount’ function, and return the number of occurrences. Once complete, write some code to test your ‘numCount’ function.

One solution

One thing to note here is that the persistent memory in this case is not count, the variable that keeps track of how many numbers are present, but the argument for num, the parameter that is passed in. Basically, numCount has to remember num so that the function inner can look for it each time a different string is passed to it.

//i: number
//o: number of times number appeared in string passed into return fucnction

// declare funciton numcount which takes in a number as arg
function numCount(num){
	// return functio which takes a string as an arg
  function inner(str){
		// delcare count variable to zero
    let count = 0;
		// loop through string, char by char
    for (let i = 0; i < str.length; i++ ){
			// if char is equal to passed in number
      if (Number(str[i]) === num) {
        // increment count by 1
        count++;
      }
    }
    // return count
    return count;
  }
  return inner;
}

const test = numCount(5);
console.log(test("y5ll5")) // 2
const test2 = numCount(9);
console.log(test("afdsre")) // 0