POST-запрос не взаимодействует с сайтом

function getMetaContentByName(name, content) {
  var content = (content == null) ? 'content' : content;
  return document.querySelector("meta[name='" + name + "']").getAttribute(content);
}

let metaTag = getMetaContentByName("viewport", "content")
console.log(metaTag)

let width = window.screen.width
console.log(width)

<meta name="viewport" content="initial-scale=0.4, width=400">

let screen = {
  width: window.screen.width,
  height: window.screen.height
}

if (screen.width < 480) {
 document.getElementById("viewport").setAttribute("content", "initial-scale=0.4, width=480");
} else if (screen.width < 720) {
 document.getElementById("viewport").setAttribute("content", "initial-scale=0.7, width=720");
} 

<meta id="viewport" name=viewport content="width=device-width; initial-scale=1">