JSFiddle - React, Tailwind, and code Playground

JavaScript

var obj = '<?xml version=\'1.0\' encoding=\'utf-8\'?><soapenv:Envelope xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/"><soapenv:Header /><soapenv:Body> <tns:getFilteredCIsByTypeResponse xmlns:ns0="http://schemas.hp.com/ucmdb/1/types" xmlns:ns1="http://schemas.hp.com/ucmdb/ui/1/types" xmlns:ns2="http://schemas.hp.com/ucmdb/1/types/query" xmlns:ns3="http://schemas.hp.com/ucmdb/1/types/props" xmlns:ns4="http://schemas.hp.com/ucmdb/1/types/classmodel" xmlns:ns5="http://schemas.hp.com/ucmdb/1/types/impact" xmlns:ns6="http://schemas.hp.com/ucmdb/1/types/update" xmlns:ns7="http://schemas.hp.com/ucmdb/discovery/1/types" xmlns:ns8="http://schemas.hp.com/ucmdb/1/types/history" xmlns:tns="http://schemas.hp.com/ucmdb/1/params/query"><tns:CIs><ns0:CI><ns0:ID>4d030502995a00afd989d3aeca2c990c</ns0:ID><ns0:type>nt</ns0:type><ns0:props><ns0:strProps><ns0:strProp><ns0:name>name</ns0:name><ns0:value>prodoo</ns0:value></ns0:strProp></ns0:strProps><ns0:booleanProps><ns0:booleanProp><ns0:name>host_iscomplete</ns0:name><ns0:value>false</ns0:value></ns0:booleanProp></ns0:booleanProps></ns0:props></ns0:CI></tns:CIs><tns:chunkInfo><ns0:numberOfChunks>0</ns0:numberOfChunks><ns0:chunksKey><ns0:key1 /><ns0:key2 /></ns0:chunksKey></tns:chunkInfo></tns:getFilteredCIsByTypeResponse></soapenv:Body></soapenv:Envelope>';

var open = '<ns0:ID>';
var close = '</ns0:ID>';

var start = obj.indexOf(open) + open.length;
var end = obj.indexOf(close);

console.log(obj.slice(start, end));