test-1.html

<html>

<head>

</head>

<body>
<label>
Output
</label>
<per id="output">

<per>
<script>
let obj = `{
   "data":"Name=Fuad, Pos=mgr, Name=Micheal, Pos=Dev, Name=Magdy, Pos=Mgr, Name=Ahmed, Pos=Dev"
}`;

let myData = JSON.parse(obj);
let arrData = myData.data.match(/Name\=(\w+), Pos\=(\w+)/g);

let result = (jobTitle)=> arrData.filter(e => e.includes(`Pos=${jobTitle}`));

document.getElementById("output").innerText = result("Dev")
</script>
</body>

</html>