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How to Add CSS Rules to a Stylesheet with JavaScript?
The insertRule() helps us add a rule at a defined position in the stylesheet while deleteRule() deletes a specific style on a web page. The following examples illustrate CSS rules that can be added to a stylesheet using JavaScript.
Insert a Rule
To insert a rule at a defined position, use the insertRule() method. The margin, padding, and box-shadow is also set. First, the custom id is set using the getElementById() −
let newSheet = document.getElementById('custom').sheet let cs = 'p {'; cs += 'margin: 4%;'; cs += 'padding: 2%;'; cs += 'font-size: 22px;'; cs += 'box-shadow: -10px 4px 0 chartreuse;' cs += '}'; newSheet.insertRule(cs, 0);
The custom is the id set using the <style> −
<style type="text/css" id="custom">
Example
Let us see the example to insert a rule on a web page −
<!DOCTYPE html> <html> <head> <style type="text/css" id="custom"> body { background-color: silver; } </style> </head> <body> <h1>Custom CSS!</h1> <p>Woohoo!</p> <script> let newSheet = document.getElementById('custom').sheet let cs = 'p {'; cs += 'margin: 4%;'; cs += 'padding: 2%;'; cs += 'font-size: 22px;'; cs += 'box-shadow: -10px 4px 0 chartreuse;' cs += '}'; newSheet.insertRule(cs, 0); </script> </body> </html>
Delete a Rule
To delete a rule at a defined position, use the deleteRule() method. First, set the rule using the insertRule() method. The <h2> border is set for the rule −
let mySheet = document.getElementById('demo').sheet let cs = 'h2 { border: 2px solid green; }' mySheet.deleteRule(2); mySheet.insertRule(cs, 0);
The demo is the id set using the <style> −
<style type="text/css" id="demo">
Example
Let us see the example to delete a rule from a web page −
<!DOCTYPE html> <html> <head> <style type="text/css" id="demo"> div { margin: 3%; text-align: center; background-color: powderblue; } p { box-shadow: 0 0 12px rgba(0,0,0,0.6); } h2 { color: red; } </style> </head> <body> <div> <h2>Custom CSS!</h2> <p>Woohoo!</p> </div> <script> let mySheet = document.getElementById('demo').sheet let cs = 'h2 { border: 2px solid green; }' mySheet.deleteRule(2); mySheet.insertRule(cs, 0); </script> </body> </html>