Javascript all in one function to find value in array

Question

is 2 days that I try but with no luck! Lol

My noob question is

I've a container

var container = [1.29,1.30,1.20,1.21,1.95,4.19,1.53,4.11,1.06,84.64,0,23.1,1,22,1.22];

So, I need to find a fast solution to look inside this container and count value, I've to respect only 2 rules If the value I have to count is 0, I need to know exactly how many 0 there's in the container If the value is not a 0, I need to count all value equal or greater that this value

So I tried this 2 ways, but in both case I got the wrong result for the 0 value.

function count(arr, value) {
   if (arr.length === 1) {
      return arr[0] === value ? 1 : 0;
   } else {
     if (value === 0) {
       return (arr.shift() === value ? 1 : 0) + count(arr, value);
     } else {
       return (arr.shift() >= value ? 1 : 0) + count(arr, value);
     }
   }
}

console.log(count(container, 2));
console.log(count(container, 0));

My expectation is to find all value >= of 2 and all value === 0 But I got right result for 2 and wrong for 0

Same with this 2 variation of the same function

function isBigEnough(value) {
  return function(element, index, array) {
    if (value === 0) {
      return (element = value);
    } else {
      return (element >= value);
    }
  }
}

function isBigEnough(value) {
  if (value === 0) {
    return function(element, index, array) {
      return (element = value);
    }
  } else {
    return function(element, index, array) {
      return (element >= value);
    }
  }
}

Every time I got 0 result for the 0 value, but there's 1 in container.

Any idea? And what is the more fast aproach?

Many thanks and have a nice day.

using shift() doesn't make sense unless you were looping through array — charlietfl
– charlietfl, Commented May 27, 2017 at 15:11
@charlietfl, the problem is that shift method modify the original array like in my answer. — Mihai Alexandru-Ionut
– Mihai Alexandru-Ionut, Commented May 27, 2017 at 15:17

Mihai Alexandru-Ionut · Accepted Answer · 2017-05-27 20:48:18Z

1

You can use filter method for a more smart solution.

filter method creates a new array by appying a provided callback function for every item in the array.

If you are using ES6, try arrow functions.

var container = [1.29,1.30,1.20,1.21,1.95,4.19,1.53,4.11,1.06,84.64,0,23.1,1,22,1.22];
function count(arr, value) {
   if(value==0)
    return arr.filter(a=>a==0).length;
   return arr.filter(a=>a>=value).length;  
}
console.log(count(container, 2));
console.log(count(container, 0));

What's wrong with your function ?

The problem is that shift method modify the original array and that's the reason you got 0 result when you call the function with value 0.Please have a look to the below snippet.

var container = [1.29,1.30,1.20,1.21,1.95,4.19,1.53,4.11,1.06,84.64,0,23.1,1,22,1.22];
function count(arr, value) {
   if (arr.length === 1) {
      return arr[0] === value ? 1 : 0;
   } else {
     if (value === 0) {
       return (arr.shift() === value ? 1 : 0) + count(arr, value);
     } else {
       return (arr.shift() >= value ? 1 : 0) + count(arr, value);
     }
   }
}
console.log(count(container, 2));
console.log(container);
console.log(count(container, 0));

To solve this you have to use a copy in order to invoke the count function everytime you need.

edited May 27, 2017 at 20:48

answered May 27, 2017 at 15:03

Mihai Alexandru-Ionut

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2 Comments

Paul S. Over a year ago

count all value equal or greater you probably want to use a >= value

Jorman Franzini Over a year ago

Thanks! I think this is the quickest way to do that I need, was so simple

A. L · Accepted Answer · 2017-05-27 15:18:06Z

1

Using reduce, pretty much a one liner.

var container = [1.29,1.30,1.20,1.21,1.95,4.19,1.53,4.11,1.06,84.64,0,23.1,1,22,1.22];

let zeroes = 0;

let result = container.reduce(function(a,b){
  if (!b)
  {
    zeroes++;
  }
  return a + b;
}, 0);

console.log(result, zeroes);

answered May 27, 2017 at 15:18

A. L

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2 Comments

ste2425 Over a year ago

Why not start the reduce with an object, one property for the zero count, another for the value count. Then you don't need a variable global to the reduce.

A. L Over a year ago

@ste2425 I guess that could work too. Just depends how they want to use it.

Nina Scholz · Accepted Answer · 2017-05-27 16:55:29Z

1

You could check value, which function should be use.

function count(arr, value) {
    return arr.filter(value ? a => a >= value : a => a === 0).length;
}

var container = [1.29, 1.30, 1.20, 1.21, 1.95, 4.19, 1.53, 4.11, 1.06, 84.64, 0, 23.1, 1, 22, 1.22];

console.log(count(container, 2));
console.log(count(container, 0));

answered May 27, 2017 at 16:55

Nina Scholz

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