I am trying to bold text in my paragraph, but am not sure what to append exactly. Here is my code.

<p id="para">
  Hello World
</p>

var para = document.getElementById('para');
var bold = document.createElement('STRONG');

para.appendChild(bold);

Any thoughts?

Thanks!

I am trying to bold text in my paragraph, but am not sure what to append exactly. Here is my code.

<p id="para">
  Hello World
</p>

var para = document.getElementById('para');
var bold = document.createElement('STRONG');

para.appendChild(bold);

Any thoughts?

Thanks!

• javascript
• html

• 1 This will append <strong></strong> into your paragraph tag... it won't wrap the content within that.... Maybe something like this? jsfiddle/h61r3th9 This will copy the content, construct the strong tag ready for appending, clear the existing content and then replace it with the constructed strong tag. – NewToJS Commented Apr 6, 2017 at 23:50
• 1 Why not just style it with CSS? – j08691 Commented Apr 6, 2017 at 23:53
• 1 I'm trying to challenge myself to e at a problem from a different angle. – Brixsta Commented Apr 6, 2017 at 23:53

4 Answers 4

The strong element has to contain a textnode.

var para = document.getElementById('para'),
    bold = document.createElement('strong'),
    textnode = document.createTextNode("I'm bold!"); 
    bold.appendChild(textnode); 
    
    para.appendChild(bold);

<p id="para">
  Hello World
</p>

To replace text content with strong element:

// Get paragraph element
var para = document.getElementById('para');

// Create a strong node
var bold = document.createElement('strong');

// Get first child element of paragraph which is a text node
var textNode = para.firstChild;

// Append text to new strong node
bold.appendChild(document.createTextNode(textNode.nodeValue));

// Replace old text node with new strong node
para.replaceChild(bold, textNode);

JS Fiddle Demo: https://jsfiddle/q9mpa7ws/3/

CSS only approach: https://jsfiddle/hrecvvbj/1/

Styling with JavaScript approach: https://jsfiddle/qynek529/2/

You don't need to worry about appending a new node at all; simply alter the font-weight through JavaScript's fontWeight DOM Style Object:

document.getElementById("para").style.fontWeight = "bold";

<p id="para">
  Hello World
</p>

Hope this helps! :)

Try to keep your concerns as separated as you can. Create a css class and apply it.

// in your css
.bold {
    font-weight: bold;
}

// in your javascript
para.className = 'bold';