Calculate the factors of a positive integer using JavaScript-JS Tutorial-php.cn

Calculate the factors of a positive integer using JavaScript

藏色散人

Release： 2021-08-13 17:37:41

Original

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In "Detailed explanation of how to multiply and divide two numbers through javascript", we introduce how to multiply and divide two numbers through javascript. Interested friends can Learn and learn~

The topic of this article is "How to write a JavaScript function to calculate the factors of a positive integer"?

So what is the factor? This belongs to elementary school knowledge. Everyone should know that a factor means that the quotient of an integer a divided by an integer b (b≠0) is exactly an integer without a remainder. We say that b is a factor of a.

After understanding what a factor is, we can easily calculate the factor of a positive integer through js code.

The complete implementation code is as follows:

<!DOCTYPE html>
<html>
<head>
    <meta charset=utf-8 />
    <title></title>
</head>
<body>

<script>
    function factors(n)
    {
        var num_factors = [], i;

        for (i = 1; i <= Math.floor(Math.sqrt(n)); i += 1)
            if (n % i === 0)
            {
                num_factors.push(i);
                if (n / i !== i)
                    num_factors.push(n / i);
            }
        num_factors.sort(function(x, y)
        {
            return x - y;});  // 数字排序
        return num_factors;
    }
    console.log(factors(15));  // [1,3,5,15]
    console.log(factors(16));  // [1,2,4,8,16]
    console.log(factors(17));  // [1,17]
</script>
</body>
</html>

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We still use console.log() to view the output information, as follows:

Calculate the factors of a positive integer using JavaScript

Obviously the factors of 15, 16, and 17 are [1,3,5,15], [1,2,4,8,16], [1,17] respectively.

In the above code, the methods that everyone needs to know are:

sqrt()Method: can return the square root of a number;

→Note: The Math.pow() method can calculate any root of a number.

floor()Method: A number can be rounded down;

→Note: The floor() method performs downward rounding Rounding calculation, it returns the nearest integer that is less than or equal to the function parameter.

push()Method: One or more elements can be added to the end of the array and the new length is returned;

→Note: This method will change the length of the array. To add one or more elements to the beginning of the array, use the unshift() method.

sort()Method: used to sort the elements of the array.

→Note: The array is sorted on the original array and no copy is generated.

Finally, I would like to recommend "JavaScript Basics Tutorial" ~ Welcome everyone to learn ~

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