How do I loop a check for string in a document in Javascript?

Question

I'm trying to make a code that will search for a specific text, and if it is found it will click a button. It needs to check for the string continuously, however I am struggling to find a way for that to happen. I'm a complete newb to coding, so any help is appreciated! :)

var findMe = [
    //Test
    'Hello!',
];

function findText() {
    var text = document.querySelector('div[id=BtnText]');

    for (var i = 0; i < findMe.length; i++) {
        if (BtnText.match(findMe[i])) {
            var btnDo = document.querySelector('input[type="submit"][value="Click!"]');
            if (btnDo) {
                btnDo.click();
            }
        }
    }
}

Answer 1

Just editing your code a little bit.

I am assuming you have HTML like this?

<div id="BtnText">Hello!</div><input type="submit" value="Click!">

You will to change your code to this

var findMe = [
    //Test
    'Hello!',
];

function findText() {
    var div = document.querySelector('div[id=BtnText]');

    for (var i = 0; i < findMe.length; i++) {
        if (div.innerText.indexOf(findMe[i]) !== -1) {               
            var btnDo = document.querySelector('input[type="submit"][value="Click!"]');
            if (btnDo) {
                if (typeof btnDo.onclick == "function") {
                    btnDo.onclick.apply(elem);
                }
            }
            return true;
        }
    }
    return false;
}

If you want to check continuously. I recommend using setInterval.

var interval = setInterval(function() {
   var textFound = findText();
   if(textFound) {
       clearInterval(interval);
   }
},50);