find a text string and replace it in javascript

HTML

<div id="target1">I am the target text 1234.</div>
<div id="target2">I am the target text 1234.</div>

<div id="target3">I am the target text 5678.</div>
<div id="target4">I am the target text 5678.</div>


<button onclick="runreplace();" class="btn btn-success mb-3">run replace example #1</button>
<button onclick="runreplaceg();" class="btn btn-success mb-3">run replace global example #2</button>

Javascript

function runreplace() {
	document.body.innerHTML = document.body.innerHTML.replace('target text 1234', '<b>KruXoR</b>');
}

function runreplaceg() {
	document.body.innerHTML = document.body.innerHTML.replace(/target text 5678/g, '<b>KruXoR</b>');
}