Step by Step solution about How to resolve the algorithm Averages/Arithmetic mean step by step in the JavaScript programming language

Both responses provide detailed explanations of the provided JavaScript code examples that calculate the mean (average) of an array of numbers. They cover the different approaches used in each example, including iterative loops, the forEach method, the reduce method, and a custom mean method added to the Array prototype.

Here's a breakdown of each example:

1. Iterative Loop:

function mean(array) {
   var sum = 0, i;
   for (i = 0; i < array.length; i++) {
       sum += array[i];
   }
   return array.length ? sum / array.length : 0;
}

This function uses a loop to iterate through the array, adding each element to the sum. It checks if the array has any elements (i.e., if array.length is not zero) and returns the mean (sum divided by length) if there are elements; otherwise, it returns 0.

2. forEach Method:

function mean(array) {
   var sum = 0;
   array.forEach(function(value) {
       sum += value;
   });
   return array.length ? sum / array.length : 0;
}

This function uses the forEach method to iterate through the array, adding each element to the sum. Similar to the previous example, it checks the array length and returns the mean or 0 accordingly.

3. reduce Method:

function mean(array) {
   return !array.length ? 0
       : array.reduce(function(pre, cur, i) {
           return (pre * i + cur) / (i + 1);
       });
}

This function uses the reduce method to calculate the mean. The pre parameter represents the previous value (sum so far), cur is the current element, and i is the current index. The expression (pre * i + cur) / (i + 1) calculates the running mean as it iterates through the array. Again, it checks the array length and returns the mean or 0 as appropriate.

4. Custom mean Method on Array Prototype:

Array.prototype.mean = function() {
   return !this.length ? 0
       : this.reduce(function(pre, cur, i) {
           return (pre * i + cur) / (i + 1);
       });
}

This code adds a custom mean method to the Array prototype. It behaves similarly to the previous example, but it allows you to call the mean method directly on an array, simplifying the syntax.

5. Functional Programming Approach with Functional.reduce:

function mean(a) {
return a.length ? Functional.reduce('+', 0, a) / a.length : 0;
}

This function uses the Functional.reduce function to calculate the mean. The '+' parameter represents the addition operator, the 0 is the initial value, and the a parameter is the array. The expression Functional.reduce('+', 0, a) / a.length calculates the sum and divides it by the array length to get the mean.

6. Arrow Function with Ternary Operator:

(sample => {

   // mean :: [Num] => (Num | NaN)
   let mean = lst => {
       let lng = lst.length;

       return lng ? (
           lst.reduce((a, b) => a + b, 0) / lng
       ) : NaN;
   };
   
   return mean(sample);

})([1, 2, 3, 4, 5, 6, 7, 8, 9]);

This function uses an arrow function (lst => ...) and a ternary operator (lng ? ... : NaN) to calculate the mean. It checks if the list has any elements (i.e., if lng is not zero) and returns the mean (sum divided by length) or NaN (not a number) if the list is empty.

In summary, these code examples demonstrate different ways to calculate the mean of an array in JavaScript. The choice of approach depends on the specific requirements and preferences of the developer.

function mean(array)
{
 var sum = 0, i;
 for (i = 0; i < array.length; i++)
 {
  sum += array[i];
 }
  return array.length ? sum / array.length : 0;
}

alert( mean( [1,2,3,4,5] ) );   // 3
alert( mean( [] ) );            // 0


function mean(array) {
    var sum = 0;
    array.forEach(function(value){
        sum += value;
        });
    return array.length ? sum / array.length : 0;
    }

alert( mean( [1,2,3,4,5] ) );   // 3


function mean(array) {
    return !array.length ? 0
        : array.reduce(function(pre, cur, i) {
            return (pre * i + cur) / (i + 1);
            });
    }

alert( mean( [1,2,3,4,5] ) );   // 3
alert( mean( [] ) );            // 0


Array.prototype.mean = function() {
    return !this.length ? 0
        : this.reduce(function(pre, cur, i) {
            return (pre * i + cur) / (i + 1);
            });
    }

alert( [1,2,3,4,5].mean() );   // 3
alert( [].mean() );            // 0


function mean(a)
{
 return a.length ? Functional.reduce('+', 0, a) / a.length : 0;
}


(sample => {

    // mean :: [Num] => (Num | NaN)
    let mean = lst => {
        let lng = lst.length;

        return lng ? (
            lst.reduce((a, b) => a + b, 0) / lng
        ) : NaN;
    };
    
    return mean(sample);

})([1, 2, 3, 4, 5, 6, 7, 8, 9]);


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