How to append element after particular element in nodejs - node.js

Question

My .XMl is
<?xml version="1.0" encoding="utf-8"?>
<data>
<shell id="TX-alg1-title">Lesson 2.1</shell>
<options id="parent">
<option id="TX-alg1">TX16E_ISE_0005</option>
<option id="TX-alg1-CID">9780353053</option>
</options>
</data>
I wanted to add another shell tag after shell tag previously present in xml.
Expected O/p
<?xml version="1.0" encoding="utf-8"?>
<data>
<shell id="TX-alg1-title">Lesson 2.1</shell>
<shell id="CA-int1-title">Lesson 2.1</shell>
<options id="parent">
<option id="TX-alg1">TX16E_ISE_0005</option>
<option id="TX-alg1-CID">9780353053</option>
</options>
</data>
I am reading my .XML file in app.js as
fs.readFile( './dlo_custom_en-US.xml', function(err, data) {
});
Please advise how to append shell tag after already present shell tag in nodejs.

Answer 1

question is almost similar Regex match text between tags
node is noting except javascript at server side. almost all programming languages have regexp to find patterns. here is simplest solution but you should to study more about regexp
fs.readFile( './dlo_custom_en-US.xml', function(err, data) {
data.replace(/\<shell(.)*\<\/shell>/, "new replacement here")
});
***** updated *****
from JavaScript: How can I insert a string at a specific index
var fs =require('fs')
String.prototype.splice = function(idx, rem, str) {
return this.slice(0, idx) + str + this.slice(idx + Math.abs(rem));
};
fs.readFile( './dlo_custom_en-US.xml',"utf8", function(err, data) {
if(err) return
var index = data.lastIndexOf('</shell>')+8
console.log(index)
var data= data.splice(index,0, 'newwwwwwwwwww')
console.log(data)
fs.writeFile('./new.xml',data,(err, done)=>{
if(err) return
console.log(err, done)
})
});