How to implement square addition in javascript

In programming languages, the addition of squares is also called the sum of squares. In fact, it is the sum of the squares of each number in a set of numbers. The final result is the sum of the squares of the set of numbers.

In JavaScript, the following methods can be used to implement square addition:

Method 1: Use a for loop

Use a for loop to traverse each element in the array, Just add the squares of each element.

The implementation code is as follows:

function squareSum(arr) {
  let sum = 0;
  for (let i = 0; i < arr.length; i++) {
    sum += arr[i] * arr[i];
  }
  return sum;
}

let arr = [1, 2, 3, 4, 5];
console.log(squareSum(arr));   //输出55

Method 2: Use Array.reduce()

Use the reduce() method to accumulate each element in the array, and at the same time Just do the squaring operation.

The implementation code is as follows:

function squareSum(arr) {
  let sum = arr.reduce(function(prev, curr) {
    return prev + curr * curr;
  }, 0);
  return sum;
}

let arr = [1, 2, 3, 4, 5];
console.log(squareSum(arr));   //输出55

Method 3: Use map() and reduce() in ES6

The map() method in ES6 can map each element in the array Operate on elements, square each element, and then use the reduce() method to accumulate.

The implementation code is as follows:

function squareSum(arr) {
  let sum = arr.map(function(num) {
    return num * num;
  }).reduce(function(prev, curr) {
    return prev + curr;
  });
  return sum;
}

let arr = [1, 2, 3, 4, 5];
console.log(squareSum(arr));   //输出55

In summary, the above three methods can all implement square addition operations, and you can choose according to your own needs in actual applications.

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