const input = document.querySelector('input');

const pattern = /^\d+(\.?)\d*$/g;

​

const allowedCodes = [8, 9, 27, 35, 36, 37, 38, 39, 46, 110, 188];

​

input.addEventListener('input', onInput);

​

function onInput(e) {

    const value = this.value;

    if( !(value.match(pattern) || allowedCodes.some(code => code === e.keyCode)) ) {

        this.value = value.slice(0, -1);

    }

}

​

​