JSFiddle - React, Tailwind, and code Playground

HTML

<input id="ckb" type="checkbox" checked>
<input id="txb" type="textbox">

JavaScript

function enableElement(element) {
    $(element).removeAttr('disabled');
}

function disableElement(element) {
    $(element).attr('disabled', 'disabled');
}

function checkboxChangeHandler() {
    var checkbox = $('#ckb'),
        textbox = $('#txb');
    
    if(checkbox.is(':checked'))
    {
        enableElement(textbox);
    }
    else
    {
        disableElement(textbox);
    }
}


$('#ckb').on('change', checkboxChangeHandler);