how to convert binary string to decimal?

Question

I want to convert binary string in to digit E.g

var binary = \"1101000\" // code for 104
var digit = binary.toString(10); // Convert String or Digit (But it          


        

Answer 1

Use the radix parameter of parseInt:

var binary = "1101000";
var digit = parseInt(binary, 2);
console.log(digit);

Answer 2

function binaryToDecimal(string) {
    let decimal = +0;
    let bits = +1;
    for(let i = 0; i < string.length; i++) {
        let currNum = +(string[string.length - i - 1]);
        if(currNum === 1) {
            decimal += bits;
        }
        bits *= 2;
    }
    console.log(decimal);
}

Answer 3

Slightly modified conventional binary conversion algorithm utilizing some more ES6 syntax and auto-features:

1. Convert binary sequence string to Array (assuming it wasnt already passed as array)

2. Reverse sequence to force 0 index to start at right-most binary digit as binary is calculated right-left

3. 'reduce' Array function traverses array, performing summation of (2^index) per binary digit [only if binary digit === 1] (0 digit always yields 0)

NOTE: Binary conversion formula:

{where d=binary digit, i=array index, n=array length-1 (starting from right)}

n
∑ (d * 2^i)
i=0

let decimal = Array.from(binaryString).reverse().reduce((total, val, index)=>val==="1"?total + 2**index:total, 0);  

console.log(`Converted BINARY sequence (${binaryString}) to DECIMAL (${decimal}).`);

Answer 4

        var num = 10;

        alert("Binary " + num.toString(2));   //1010
        alert("Octal " + num.toString(8));    //12
        alert("Hex " + num.toString(16));     //a

        alert("Binary to Decimal "+ parseInt("1010", 2));  //10
        alert("Octal to Decimal " + parseInt("12", 8));    //10
        alert("Hex to Decimal " + parseInt("a", 16));      //10

Answer 5

Another implementation just for functional JS practicing could be

var bin2int = s => Array.prototype.reduce.call(s, (p,c) => p*2 + +c)
console.log(bin2int("101010"));

where +c coerces String type c to a Number type value for proper addition.

Answer 6

parseInt() with radix is a best solution (as was told by many):

But if you want to implement it without parseInt, here is an implementation:

  function bin2dec(num){
    return num.split('').reverse().reduce(function(x, y, i){
      return (y === '1') ? x + Math.pow(2, i) : x;
    }, 0);
  }