binary to decimal converter using javascript

1var digit = parseInt(binary, 2);

1let binary = 0001
2parseInt(binary, 2)
3// returns 1

1const binaryArrayToNumber = arr => {
2    let len = arr.length
3    let pow = []
4    let decimal = []
5    for(let i = 0; i <= len - 1; i++){
6        pow.unshift(i)
7    }
8    arr.forEach((x,index) => {
9        decimal.push(x*2**pow[index])
10    })
11    let toDecimal = decimal.reduce((acc, curr) => acc + curr, 0)
12    return toDecimal
13};
14console.log(binaryArrayToNumber([1, 0, 1, 1]))

1const input = document.querySelector("#input");
2const output = document.querySelector("#output");
3const btn = document.querySelector("#btn");
4const error = document.querySelector("#error-msg");
5
6
7function Bin2Dec() {
8    const regEx = /^[0-1]+$/;
9
10    if(input.value.match(regEx)) {
11        const binArr = input.value.split('').reverse();
12        let decNo = 0;
13
14        binArr.forEach((item, index) => item === '1' ? decNo += Math.pow(2, index) : void 0);
15
16        output.value = decNo.toString();
17        output.style.cursor = 'text';
18    }else {
19        error.style.display = 'block';
20    }
21}
22
23
24btn.addEventListener('click', () => {
25    error.style.display = 'none';
26    Bin2Dec();
27})