How to change the text of a label?

Try this in JS:

Clicking on the label text toggles it with an alternative text, while selecting the associated input field and giving the focus to the same associated input field.

<script type="text/javascript">"use strict";
const oldLabelText="ORIGINAL BUTTON TAG TEXT";
document.write(
'<label id=labId for=inputId onClick="changeText(this.id)">'+oldLabelText+'</label>:<br>'+
'<input id="inputId" value="The input value" />'
);
</script>

<script type="text/javascript">"use strict";
const stat=[oldLabelText,"NEW LABEL TEXT","THIRD LABEL TEXT","FOURTH LABEL TEXT"];
let cptr=0;

function changeText(button_id){
var el = document.getElementById(button_id);

el.textContent = stat[++cptr % (stat.length)];

// or
// el.firstChild.data = stat[++cptr % (stat.length)];

// or
// el.innerHTML = stat[++cptr % (stat.length)];

// or simply
// el.innerHTML = "the new text";
}
</script>