JavaScript get textContent excluding children

Using only JavaScript (you specified you cannot use jQuery), and given that you have provided and know the id for the parent element:

document.getElementById('parent_element_id').childNodes[0].nodeValue;

You can also use .trim() to remove any trailing space characters left behind from the removal of any child element text:

document.getElementById('parent_element_id').childNodes[0].nodeValue.trim();

You can solve using DOM API as childNodes and nodeType.

var elChildNode = document.querySelector("#hello").childNodes;
var sChildTextSum = "";

elChildNode.forEach(function(value){
    if(value.nodeType === Node.TEXT_NODE) { 
        console.log("Current textNode value is : ", value.nodeValue.trim());
        sChildTextSum += value.nodeValue;
    }
}); 

console.log("All text value of firstChild : ", sChildTextSum);

I created a sample code as above.

https://jsfiddle.net/nigayo/p7t9bdc3/

var mydiv = getElementByID("id");
function Get_text(element) {
    var selected = element.cloneNode(true);
    var text;
    while (selected.firstChild) {
      if (selected.firstChild.nodeType == 3) text = selected.firstChild.nodeValue;
      selected.removeChild(selected.firstChild);
    }
    return text;
  }
Get_text(mydiv);

To get Author's Name from the following element, excluding <span>...:

<div class="details__instructor">
    Author's Name<span ng-show="job_title">, Entrepreneur</span>
</div>

use childNodes[0]. For example:

document.querySelector('div.details__instructor').childNodes[0].textContent