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JavaScript in Detail: From Beginner to Advanced

Solution: Know Your Browser

Exercise solution to "Know Your Browser." where the solution leverages DOM and BOM to create a final webpage with all specified information

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Solution

The final solution to the problem is here.

The above solution shows that we do not alter any elements on HTML directly. Instead, use JavaScript to add/remove elements to DOM and fetch certain information through BOM. Let’s see more detail below.

Node.js
// delete all elements with h2 tag
var del1 = document.getElementsByTagName('h2');
for(var i = 0; i < del1.length; i++){
    del1[i].parentNode.removeChild(del1[i]);
}
// delete all elements with p tag
var del2 = document.getElementsByTagName('p');
for(var i = 0; i < del2.length; i++){
    del2[i].parentNode.removeChild(del2[i]);
}
// Adding browser name
var browserEle = document.getElementById('browserName');
browserEle.firstChild.nodeValue = 'Browser name: ' + window.navigator.appName;
// Adding area of outer window size
var areaEle = document.getElementById('windowSize');
areaEle.firstChild.nodeValue = 'Area of the window: ' + (window.outerHeight * window.outerWidth);
// URL information element
var newEle1 = document.createElement('p');
var content1 = document.createTextNode(`HostName: ${window.location.hostname}\n`);
newEle1.appendChild(content1);
// full url
var newEle2 = document.createElement('p');
var content2 = document.createTextNode(`URL: ${window.location.href}\n`);
newEle2.appendChild(content2);
// Add to body
var body = document.getElementById('target');
body.appendChild(newEle1); // add hostName
body.appendChild(newEle2); // add URL

In the above code, do the following.

  • Delete elements with tag names 'p' and 'h2'. The HTML page shows that these elements should be deleted. But do the following for both:

    1. Fetch all elements with tag names for 'h2' (line 2) and 'p' (line 7) with document.getElementsByTagName method.

    2. Because of a NodeList, iterate the list using a for loop for both. ...