JavaScript fun: Binary statistics

If we are engaged in front-end operations, we must have little chance to access binary data. What bitwise operations are, isn't it a problem that the underlying layer should consider? If we are engaged in front-end operations, we must have little chance to access binary data. What bitwise operations are, isn't it a problem that the underlying layer should consider?

I saw a question yesterday. It is related to binary, but it does not matter with bitwise operations. It can be easily solved with the help of JS's language features.

Description:

Write a function that receives a decimal positive integer as a parameter and represents it in binary format. Then, return the numbers equal to 1.

Here is an example:

1234Binary is10011010010.5Items1, So return5.

After reading this description, my first thought in my mind was how to convert it from decimal to binary (hate less ^_^ when the book was used ).

Fortunately, I have a good memory and soon thought of it.2Return the remainder and divide it2.2Return the remainder and divide it2... Until the result is0.

In the above process, use a variable to record the remainder1.

So we have the following practices:

var countBits = function(n) {    var count = 0;    while(n > 0){        var res = n % 2;        if(res == 1){            count++;        }        n = parseInt(n / 2);    }    return count;};

This code and IDEA are both quite satisfactory, but they do not fully utilize the language features of JavaScript.

In JS, isn't there a ready-made API for converting decimal to binary?

Number. toString (2)In this case, will the binary string be obtained?

If all the results are returned, you can find the number 1 one by one and then return the result.

Well, the two methods above are both good, but the most efficient method is bitwise.

Finally, let's take a look at a bit operation solution written by a foreign Daniel!

function countBits(n) {  for(c=0;n;n>>=1)c+=n&1  return c;}

Bright and blind eyes.

The above is JavaScript fun: Count the binary content. For more information, see the PHP Chinese website (www.php1.cn )!