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Javascript - how to render an output by typing three (or more) alphabets into the input?

I am making an html page which is a typer of a foreign script.
my progress: HERE
Here's the entire javascript:
function getReplacedText(latinText) {
if (!latinText) {
return "";
}
var replacedText = "";
for (var i = 0, len = latinText.length; i < len; i++) {
var curLetter = latinText[i];
var pos1Txt = latinText[i + 1];
var pos2Txt = latinText[i + 2];
if (!(curLetter == "")) {
var dualLetter = latreplaced[curLetter + pos1Txt];
if (dualLetter) {
replacedText += dualLetter;
i++;
continue;
}
}
replacedText += latreplaced[curLetter] || curLetter;
}
return replacedText;
}
var latreplaced = {
"u":"う",
"ku":"く",
"tsu":"つ",
};
function onLatinTextChange(txt) {
var replacedTextareaElem = document.getElementById("replaced_textarea");
var div = document.createElement("div");
var replacedHtmlEntities = getReplacedText(txt);
div.innerHTML = replacedHtmlEntities;
replacedTextareaElem.value = div.innerText;
}
The purpose of this project is to create a virtual phonetic keyboard to type certain forign scripts by only using Latin alphabets, without its keyboard setting installed.
Basically, if you enter an alphabet into the input <textarea>, it renders its corresponding foreign alphabet. (For instance, input 'u' > output 'う', input 'ku' > output 'く')
Here is my problem: So far I have enabled rendering an output when one or two alphabet is typed into the input box. But I cannot figure out how to enable the same by entering three alphabets. (For instance, input 'tsu' > output 'つ')
"u":"う", // <- can convert
"ku":"く", // <- can convert
"tsu":"つ", // <- cannot convert!
In the javascript code, there is a var called dualLetter, which goes by the following script:
var dualLetter = latreplaced[curLetter + pos1Txt];
How can I edit this part of code (or the entire javascript) to be able to convert 3 or more input alphabets? Do I need to make var tripleLetter, or create a whole new system? Any alternative ways would also be helpful.

[edit] a solution inspired by your code :
I changed the main function but this definitively works
live demo : https://jsfiddle.net/alias_gui3/wds426mq/12/
source code :
var dictionnary = {
"u":"う",
"ku":"く",
"tsu":"つ",
"test for spaces": "😍"
};
var maxLength = Object.keys(dictionnary)
.reduce((a, b) => a.length > b.length ? a : b) // get the longest word
.length; // and it's length
function translate (text) {
var translated = "";
var cur = 0;
while (cur < text.length) {
var testedPhoneme;
var symbol = undefined;
for (var length = maxLength; length > 0; length --) {
testedPhoneme = text.substr(cur, length);
if (dictionnary[testedPhoneme]) {
symbol = dictionnary[testedPhoneme];
break; // stop the loop
}
}
if (symbol) {
translated += symbol;
cur += testedPhoneme.length;
}
else {
translated += text[cur]
cur++;
}
}
return translated
}
function onLatinTextChange(txt) {
var replacedTextareaElem = document.getElementById("replaced_textarea");
var div = document.createElement("div");
var replacedHtmlEntities = translate(txt);
div.innerHTML = replacedHtmlEntities;
replacedTextareaElem.value = div.innerText;
}
[previous post] a simple solution :
I suggest you split your text using spaces
If i understand well, you want to type u ku tsu to get うくつ, not ukutsu, if this is right then something like that could work :
const dictionnary = {
"u": "う",
"ku": "く",
"tsu": "つ"
var phonemes = text.split(' ') // split text by spaces
var translatedArray = phonemes.map(function (phoneme) {
return dictionnary[phoneme] || phoneme
// will return the latin phoneme if it is not in the dictionnary
})
translatedString = translatedArray.join('')

String.replace callback not working

I'm trying to make a class to convert bbcode to html but replace doesn't call callback function.
Here's what i have
function bbcode(){
this.bbcode_table = {};
this.bbcode_table[/[asdf]/g] = function(match, contents, offset, input_string){
return "hi";
}
}
bbcode.prototype.toHTML = function(str){
for (var key in this.bbcode_table){
str = str.replace(key, this.bbcode_table[key]);
}
console.log(str); // asdf
}
var a = new bbcode;
a.toHTML("asdf");
The code above is not working, however, the code below works well.
text = "asdf";
text = text.replace(/[asdf]/g, function(match, contents, offset, input_string){
return "hi";
});
console.log(text); // hihihihi
What am I doing wrong?

Because the key is converted to string, so the funtion replace is not capturing any match with "/[asdf]/g".
You can follow this approach with the object RegExp
function bbcode() {
this.bbcode_table = {};
this.bbcode_table["[asdf]"] = {
"cb": function(match, contents, offset, input_string) {
return "hi";
},
"flag": "g"
}
}
bbcode.prototype.toHTML = function(str) {
for (var key in this.bbcode_table) {
var regex = new RegExp(key, this.bbcode_table[key].flag);
str = str.replace(regex, this.bbcode_table[key].cb);
}
console.log(str);
}
var a = new bbcode;
a.toHTML("asdf");

Javascript RegEx - Split Html-string

I'm working on a script and need to split strings which contain both html tags and text. I'm trying to isolate the text and elimanate the tags
For example, I want this:
string = '<p><span style="color:#ff3366;">A</span></p><p><span style="color:#ff3366;text-decoration:underline;">B</span></p><p><span style="color:#ff3366;text-decoration:underline;"><em>C</em></span></p>';
to be split like this:
separation = string.split(/some RegExp/);
and become:
separation[0] = "<span style="color:#ff3366;">A</span>";
separation[1] = "<span style="color:#ff3366;text-decoration:underline;">B</span>";
separation[2] = "<span style="color:#ff3366;text-decoration:underline;"><em>C</em></span>";
After that I would like to split the sepeartion string like this:
stringNew = '<span style="color:#ff3366;">A</span>';
extendedSeperation = stringNew.split(/some RegExp/);
extendedSeperation[0] = "A";
extendedSeperation[1] = "style="color:#ff3366;";

Don't use RegEx for reasons explained in comments.
Instead, do this:
Create an invisible node:
node = $("<div>").css("display", "none");
Attach it to the body:
$("body").append(node);
Now inject your HTML into the node:
node.html(myHTMLString);
Now you can traverse the DOM tree and extract/render it as you like, much like this:
ptags = node.find("p") // will return all <p> tags
To get the content of a tag use:
ptags[0].html()
Finally, to clear the node do:
node.html("");
This should be enough to get you going.
This way you leverage the internal parser of the browser, as suggested in the comments.

Your exact expectations are a little unclear, but based only on the information given here is an example that may give you ideas.
Does not use RegExp
Does not use jQuery or any other library
Does not append and remove elements from the DOM
Is well supported across browsers
function walkTheDOM(node, func) {
func(node);
node = node.firstChild;
while (node) {
walkTheDOM(node, func);
node = node.nextSibling;
}
}
function textContent(node) {
if (typeof node.textContent !== "undefined" && node.textContent !== null) {
return node.textContent;
}
var text = ""
walkTheDOM(node, function (current) {
if (current.nodeType === 3) {
text += current.nodeValue;
}
});
return text;
}
function dominate(text) {
var container = document.createElement('div');
container.innerHTML = text;
return container;
}
function toSeparation(htmlText) {
var spans = dominate(htmlText).getElementsByTagName('span'),
length = spans.length,
result = [],
index;
for (index = 0; index < length; index += 1) {
result.push(spans[index].outerHTML);
}
return result;
}
function toExtendedSeperation(node) {
var child = dominate(node).firstChild,
attributes = child.attributes,
length = attributes.length,
text = textContent(child),
result = [],
style,
index,
attr;
if (text) {
result.push(text);
}
for (index = 0; index < length; index += 1) {
attr = attributes[index]
if (attr.name === 'style') {
result.push(attr.name + '=' + attr.value);
break;
}
}
return result;
}
var strHTML = '<p><span style="color:#ff3366;">A</span></p><p><span style="color:#ff3366;text-decoration:underline;">B</span></p><p><span style="color:#ff3366;text-decoration:underline;"><em>C</em></span></p>',
separation = toSeparation(strHTML),
extendedSeperation = toExtendedSeperation(separation[0]),
pre = document.getElementById('out');
pre.appendChild(document.createTextNode(JSON.stringify(separation, null, 2)));
pre.appendChild(document.createTextNode('\n\n'));
pre.appendChild(document.createTextNode(JSON.stringify(extendedSeperation, null, 2)));
<pre id="out"></pre>
Of course you will need to make modifications to suit your exact needs.

.read .write .replace string elements in jQuery

I have these 2 functions (serialize and deserialize) in Javascript (below) and I want to change it to jQuery. I am wondering what would the right replacement for read and write in jQuery. Read and write strings are from and to a Textarea. This is part of Openlayers vector formats, getting geometries into / from OL map canvas.
Serialize is outputing the geometries from mapcanvas to textarea.
function serialize(feature) {
var type = document.getElementById("formatType").value;
var pretty = document.getElementById("prettyPrint").checked;
var str = formats['out'][type].write(feature, pretty);
str = str.replace(/,/g, ', ');
document.getElementById('output').value = str;
}
Deserialize is reading string from Textarea into OL mapcanvas.
function deserialize() {
var element = document.getElementById('text');
var type = document.getElementById("formatType").value;
var features = formats['in'][type].read(element.value);
var bounds;
if(features) {
if(features.constructor != Array) {
features = [features];
}
for(var i=0; i<features.length; ++i) {
if (!bounds) {
bounds = features[i].geometry.getBounds();
} else {
bounds.extend(features[i].geometry.getBounds());
}
}
vectors.addFeatures(features);
map.zoomToExtent(bounds);
var plural = (features.length > 1) ? 's' : '';
element.value = features.length + ' feature' + plural + ' added';
} else {
element.value = 'Bad input ' + type;
}
}
Thanks in advance.
Again, I am asking about the read and write function equivalent in jQuery. These 2 lines:
var str = formats['out'][type].write(feature, pretty);
var features = formats['in'][type].read(element.value);

to get the text in a text area
$("#myTextArea").val();
To set it to something
$("#myTextArea").val("Foo bar.");

Pretty printing XML with javascript

I have a string that represents a non indented XML that I would like to pretty-print. For example:
<root><node/></root>
should become:
<root>
<node/>
</root>
Syntax highlighting is not a requirement. To tackle the problem I first transform the XML to add carriage returns and white spaces and then use a pre tag to output the XML. To add new lines and white spaces I wrote the following function:
function formatXml(xml) {
var formatted = '';
var reg = /(>)(<)(\/*)/g;
xml = xml.replace(reg, '$1\r\n$2$3');
var pad = 0;
jQuery.each(xml.split('\r\n'), function(index, node) {
var indent = 0;
if (node.match( /.+<\/\w[^>]*>$/ )) {
indent = 0;
} else if (node.match( /^<\/\w/ )) {
if (pad != 0) {
pad -= 1;
}
} else if (node.match( /^<\w[^>]*[^\/]>.*$/ )) {
indent = 1;
} else {
indent = 0;
}
var padding = '';
for (var i = 0; i < pad; i++) {
padding += ' ';
}
formatted += padding + node + '\r\n';
pad += indent;
});
return formatted;
}
I then call the function like this:
jQuery('pre.formatted-xml').text(formatXml('<root><node1/></root>'));
This works perfectly fine for me but while I was writing the previous function I thought that there must be a better way. So my question is do you know of any better way given an XML string to pretty-print it in an html page? Any javascript frameworks and/or plugins that could do the job are welcome. My only requirement is this to be done on the client side.

This can be done using native javascript tools, without 3rd party libs, extending the #Dimitre Novatchev's answer:
var prettifyXml = function(sourceXml)
{
var xmlDoc = new DOMParser().parseFromString(sourceXml, 'application/xml');
var xsltDoc = new DOMParser().parseFromString([
// describes how we want to modify the XML - indent everything
'<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform">',
' <xsl:strip-space elements="*"/>',
' <xsl:template match="para[content-style][not(text())]">', // change to just text() to strip space in text nodes
' <xsl:value-of select="normalize-space(.)"/>',
' </xsl:template>',
' <xsl:template match="node()|#*">',
' <xsl:copy><xsl:apply-templates select="node()|#*"/></xsl:copy>',
' </xsl:template>',
' <xsl:output indent="yes"/>',
'</xsl:stylesheet>',
].join('\n'), 'application/xml');
var xsltProcessor = new XSLTProcessor();
xsltProcessor.importStylesheet(xsltDoc);
var resultDoc = xsltProcessor.transformToDocument(xmlDoc);
var resultXml = new XMLSerializer().serializeToString(resultDoc);
return resultXml;
};
console.log(prettifyXml('<root><node/></root>'));
Outputs:
<root>
<node/>
</root>
JSFiddle
Note, as pointed out by #jat255, pretty printing with <xsl:output indent="yes"/> is not supported by firefox. It only seems to work in chrome, opera and probably the rest webkit-based browsers.

From the text of the question I get the impression that a string result is expected, as opposed to an HTML-formatted result.
If this is so, the simplest way to achieve this is to process the XML document with the identity transformation and with an <xsl:output indent="yes"/> instruction:
<xsl:stylesheet version="1.0"
xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
<xsl:output omit-xml-declaration="yes" indent="yes"/>
<xsl:template match="node()|#*">
<xsl:copy>
<xsl:apply-templates select="node()|#*"/>
</xsl:copy>
</xsl:template>
</xsl:stylesheet>
When applying this transformation on the provided XML document:
<root><node/></root>
most XSLT processors (.NET XslCompiledTransform, Saxon 6.5.4 and Saxon 9.0.0.2, AltovaXML) produce the wanted result:
<root>
<node />
</root>

Found this thread when I had a similar requirement but I simplified OP's code as follows:
function formatXml(xml, tab) { // tab = optional indent value, default is tab (\t)
var formatted = '', indent= '';
tab = tab || '\t';
xml.split(/>\s*</).forEach(function(node) {
if (node.match( /^\/\w/ )) indent = indent.substring(tab.length); // decrease indent by one 'tab'
formatted += indent + '<' + node + '>\r\n';
if (node.match( /^<?\w[^>]*[^\/]$/ )) indent += tab; // increase indent
});
return formatted.substring(1, formatted.length-3);
}
works for me!

Slight modification of efnx clckclcks's javascript function. I changed the formatting from spaces to tab, but most importantly I allowed text to remain on one line:
var formatXml = this.formatXml = function (xml) {
var reg = /(>)\s*(<)(\/*)/g; // updated Mar 30, 2015
var wsexp = / *(.*) +\n/g;
var contexp = /(<.+>)(.+\n)/g;
xml = xml.replace(reg, '$1\n$2$3').replace(wsexp, '$1\n').replace(contexp, '$1\n$2');
var pad = 0;
var formatted = '';
var lines = xml.split('\n');
var indent = 0;
var lastType = 'other';
// 4 types of tags - single, closing, opening, other (text, doctype, comment) - 4*4 = 16 transitions
var transitions = {
'single->single': 0,
'single->closing': -1,
'single->opening': 0,
'single->other': 0,
'closing->single': 0,
'closing->closing': -1,
'closing->opening': 0,
'closing->other': 0,
'opening->single': 1,
'opening->closing': 0,
'opening->opening': 1,
'opening->other': 1,
'other->single': 0,
'other->closing': -1,
'other->opening': 0,
'other->other': 0
};
for (var i = 0; i < lines.length; i++) {
var ln = lines[i];
// Luca Viggiani 2017-07-03: handle optional <?xml ... ?> declaration
if (ln.match(/\s*<\?xml/)) {
formatted += ln + "\n";
continue;
}
// ---
var single = Boolean(ln.match(/<.+\/>/)); // is this line a single tag? ex. <br />
var closing = Boolean(ln.match(/<\/.+>/)); // is this a closing tag? ex. </a>
var opening = Boolean(ln.match(/<[^!].*>/)); // is this even a tag (that's not <!something>)
var type = single ? 'single' : closing ? 'closing' : opening ? 'opening' : 'other';
var fromTo = lastType + '->' + type;
lastType = type;
var padding = '';
indent += transitions[fromTo];
for (var j = 0; j < indent; j++) {
padding += '\t';
}
if (fromTo == 'opening->closing')
formatted = formatted.substr(0, formatted.length - 1) + ln + '\n'; // substr removes line break (\n) from prev loop
else
formatted += padding + ln + '\n';
}
return formatted;
};

Personnaly, I use google-code-prettify with this function :
prettyPrintOne('<root><node1><root>', 'xml')

Or if you'd just like another js function to do it, I've modified Darin's (a lot):
var formatXml = this.formatXml = function (xml) {
var reg = /(>)(<)(\/*)/g;
var wsexp = / *(.*) +\n/g;
var contexp = /(<.+>)(.+\n)/g;
xml = xml.replace(reg, '$1\n$2$3').replace(wsexp, '$1\n').replace(contexp, '$1\n$2');
var pad = 0;
var formatted = '';
var lines = xml.split('\n');
var indent = 0;
var lastType = 'other';
// 4 types of tags - single, closing, opening, other (text, doctype, comment) - 4*4 = 16 transitions
var transitions = {
'single->single' : 0,
'single->closing' : -1,
'single->opening' : 0,
'single->other' : 0,
'closing->single' : 0,
'closing->closing' : -1,
'closing->opening' : 0,
'closing->other' : 0,
'opening->single' : 1,
'opening->closing' : 0,
'opening->opening' : 1,
'opening->other' : 1,
'other->single' : 0,
'other->closing' : -1,
'other->opening' : 0,
'other->other' : 0
};
for (var i=0; i < lines.length; i++) {
var ln = lines[i];
var single = Boolean(ln.match(/<.+\/>/)); // is this line a single tag? ex. <br />
var closing = Boolean(ln.match(/<\/.+>/)); // is this a closing tag? ex. </a>
var opening = Boolean(ln.match(/<[^!].*>/)); // is this even a tag (that's not <!something>)
var type = single ? 'single' : closing ? 'closing' : opening ? 'opening' : 'other';
var fromTo = lastType + '->' + type;
lastType = type;
var padding = '';
indent += transitions[fromTo];
for (var j = 0; j < indent; j++) {
padding += ' ';
}
formatted += padding + ln + '\n';
}
return formatted;
};

All of the javascript functions given here won't work for an xml document having unspecified white spaces between the end tag '>' and the start tag '<'. To fix them, you just need to replace the first line in the functions
var reg = /(>)(<)(\/*)/g;
by
var reg = /(>)\s*(<)(\/*)/g;

what about creating a stub node (document.createElement('div') - or using your library equivalent), filling it with the xml string (via innerHTML) and calling simple recursive function for the root element/or the stub element in case you don't have a root. The function would call itself for all the child nodes.
You could then syntax-highlight along the way, be certain the markup is well-formed (done automatically by browser when appending via innerHTML) etc. It wouldn't be that much code and probably fast enough.

If you are looking for a JavaScript solution just take the code from the Pretty Diff tool at http://prettydiff.com/?m=beautify
You can also send files to the tool using the s parameter, such as:
http://prettydiff.com/?m=beautify&s=https://stackoverflow.com/

You can get pretty formatted xml with xml-beautify
var prettyXmlText = new XmlBeautify().beautify(xmlText,
{indent: " ",useSelfClosingElement: true});
indent:indent pattern like white spaces
useSelfClosingElement: true=>use self-closing element when empty element.
JSFiddle
Original(Before)
<?xml version="1.0" encoding="utf-8"?><example version="2.0">
<head><title>Original aTitle</title></head>
<body info="none" ></body>
</example>
Beautified(After)
<?xml version="1.0" encoding="utf-8"?>
<example version="2.0">
<head>
<title>Original aTitle</title>
</head>
<body info="none" />
</example>

For a current project I had the need to prettify and colorize XML without extra libraries. The following self contained code works quite well.
function formatXml(xml,colorize,indent) {
function esc(s){return s.replace(/[-\/&<> ]/g,function(c){ // Escape special chars
return c==' '?' ':'&#'+c.charCodeAt(0)+';';});}
var sm='<div class="xmt">',se='<div class="xel">',sd='<div class="xdt">',
sa='<div class="xat">',tb='<div class="xtb">',tc='<div class="xtc">',
ind=indent||' ',sz='</div>',tz='</div>',re='',is='',ib,ob,at,i;
if (!colorize) sm=se=sd=sa=sz='';
xml.match(/(?<=<).*(?=>)|$/s)[0].split(/>\s*</).forEach(function(nd){
ob=('<'+nd+'>').match(/^(<[!?\/]?)(.*?)([?\/]?>)$/s); // Split outer brackets
ib=ob[2].match(/^(.*?)>(.*)<\/(.*)$/s)||['',ob[2],'']; // Split inner brackets
at=ib[1].match(/^--.*--$|=|('|").*?\1|[^\t\n\f \/>"'=]+/g)||['']; // Split attributes
if (ob[1]=='</') is=is.substring(ind.length); // Decrease indent
re+=tb+tc+esc(is)+tz+tc+sm+esc(ob[1])+sz+se+esc(at[0])+sz;
for (i=1;i<at.length;i++) re+=(at[i]=="="?sm+"="+sz+sd+esc(at[++i]):sa+' '+at[i])+sz;
re+=ib[2]?sm+esc('>')+sz+sd+esc(ib[2])+sz+sm+esc('</')+sz+se+ib[3]+sz:'';
re+=sm+esc(ob[3])+sz+tz+tz;
if (ob[1]+ob[3]+ib[2]=='<>') is+=ind; // Increase indent
});
return re;
}
See https://jsfiddle.net/dkb0La16/

Or just print out the special HTML characters?
Ex: <xmlstuff>
<node />
</xmlstuff>
Horizontal tab
Line feed

XMLSpectrum formats XML, supports attribute indentation and also does syntax-highlighting for XML and any embedded XPath expressions:
XMLSpectrum is an open source project, coded in XSLT 2.0 - so you can run this server-side with a processor such as Saxon-HE (recommended) or client-side using Saxon-CE.
XMLSpectrum is not yet optimised to run in the browser - hence the recommendation to run this server-side.

here is another function to format xml
function formatXml(xml){
var out = "";
var tab = " ";
var indent = 0;
var inClosingTag=false;
var dent=function(no){
out += "\n";
for(var i=0; i < no; i++)
out+=tab;
}
for (var i=0; i < xml.length; i++) {
var c = xml.charAt(i);
if(c=='<'){
// handle </
if(xml.charAt(i+1) == '/'){
inClosingTag = true;
dent(--indent);
}
out+=c;
}else if(c=='>'){
out+=c;
// handle />
if(xml.charAt(i-1) == '/'){
out+="\n";
//dent(--indent)
}else{
if(!inClosingTag)
dent(++indent);
else{
out+="\n";
inClosingTag=false;
}
}
}else{
out+=c;
}
}
return out;
}

Xml formatting can be done by parsing the xml, adding or changing text nodes in the dom tree for indentation and then serializing the DOM back to xml.
Please check formatxml function in https://jsonbrowser.sourceforge.io/formatxml.js
You can see the function in action in https://jsonbrowser.sourceforge.io/
under the Xml tab.
Below is the simplified code.
formatxml.js adds error checking, optional removal of comments, indent as a parameter and handles non-space text between parent nodes.
const parser = new DOMParser();
const serializer = new XMLSerializer();
function formatXml(xml) {
let xmlDoc = parser.parseFromString(xml, 'application/xml');
let rootElement = xmlDoc.documentElement;
indentChildren(xmlDoc, rootElement, "\n", "\n ");
xml = serializer.serializeToString(xmlDoc);
return xml;
}
function indentChildren(xmlDoc, node, prevPrefix, prefix) {
let children = node.childNodes;
let i;
let prevChild = null;
let prevChildType = 1;
let child = null;
let childType;
for (i = 0; i < children.length; i++) {
child = children[i];
childType = child.nodeType;
if (childType != 3) {
if (prevChildType == 3) {
// Update prev text node with correct indent
prevChild.nodeValue = prefix;
} else {
// Create and insert text node with correct indent
let textNode = xmlDoc.createTextNode(prefix);
node.insertBefore(textNode, child);
i++;
}
if (childType == 1) {
let isLeaf = child.childNodes.length == 0 || child.childNodes.length == 1 && child.childNodes[0].nodeType != 1;
if (!isLeaf) {
indentChildren(xmlDoc, child, prefix, prefix + " ");
}
}
}
prevChild = child;
prevChildType =childType;
}
if (child != null) {
// Previous level indentation after last child
if (childType == 3) {
child.nodeValue = prevPrefix;
} else {
let textNode = xmlDoc.createTextNode(prevPrefix);
node.append(textNode);
}
}
}
Reference: https://www.w3schools.com/XML/dom_intro.asp

var formatXml = this.formatXml = function (xml) {
var reg = /(>)(<)(\/*)/g;
var wsexp = / *(.*) +\n/g;
var contexp = /(<.+>)(.+\n)/g;
xml = xml.replace(reg, '$1\n$2$3').replace(wsexp, '$1\n').replace(contexp, '$1\n$2');
var pad = 0;
var formatted = '';
var lines = xml.split('\n');
var indent = 0;
var lastType = 'other';

var reg = /(>)\s*(<)(\/*)/g;
xml = xml.replace(/\r|\n/g, ''); //deleting already existing whitespaces
xml = xml.replace(reg, '$1\r\n$2$3');

Use above method for pretty print and then add this in any div by using jquery text() method. for example id of div is xmldiv then use :
$("#xmldiv").text(formatXml(youXmlString));

You could also use Saxon-JS client-side:
<script src="SaxonJS/SaxonJS2.js"></script>
<script>
let myXML = `<root><node/></root>`;
SaxonJS.getResource({
text: myXML.replace(`xml:space="preserve"`, ''),
type: "xml"
}).then(doc => {
const output = SaxonJS.serialize(doc, {method: "xml", indent: true, "omit-xml-declaration":true});
console.log(output);
})
</script>
Saxon-JS Installation client-side
Saxon-JS Download page

This may involve creating nodes as objects, but you can have total control over exporting pretty formatted xml.
The following will return a string array of the lines which you can join with a new line delimiter "\n".
/**
* The child of an XML node can be raw text or another xml node.
*/
export type PossibleNode = XmlNode | string;
/**
* Base XML Node type.
*/
export interface XmlNode {
tag: string;
attrs?: { [key: string]: string };
children?: PossibleNode[];
}
/**
* Exports the given XML node to a string array.
*
* #param node XML Node
* #param autoClose Auto close the tag
* #param indent Indentation level
* #returns String array
*/
export function xmlNodeToString(
node: XmlNode,
autoClose: boolean = true,
indent: number = 0
): string[] {
const indentStr = " ".repeat(indent);
const sb: string[] = [];
sb.push(`${indentStr}<${node.tag}`);
if (node.attrs) {
for (const key in node.attrs) {
sb.push(`${indentStr} ${key}="${node.attrs[key]}"`);
}
}
if (node.children) {
if (node.children.length === 1 && typeof node.children[0] === "string") {
sb[sb.length - 1] += ">" + node.children[0];
} else {
sb.push(`${indentStr}>`);
for (const child of node.children) {
if (typeof child === "string") {
sb.push(`${indentStr} ${child}`);
} else {
const lines = xmlNodeToString(child, autoClose, indent + 1);
sb.push(...lines.map((line) => `${indentStr} ${line}`));
}
}
}
if (autoClose) {
if (node.children.length === 1 && typeof node.children[0] === "string") {
sb[sb.length - 1] += `</${node.tag}>`;
} else {
sb.push(`${indentStr}</${node.tag}>`);
}
}
} else {
if (autoClose) {
sb.push(`${indentStr}/>`);
} else {
sb.push(`${indentStr}>`);
}
}
return sb;
}
Updates appreciated on the gist: https://gist.github.com/rodydavis/acd609560ab0416b60681fddabc43eee

Xml-to-json library has method formatXml(xml). I am the maintainer of the project.
var prettyXml = formatXml("<a><b/></a>");
// <a>
// <b/>
// </a>

This my version, maybe usefull for others, using String builder
Saw that someone had the same piece of code.
public String FormatXml(String xml, String tab)
{
var sb = new StringBuilder();
int indent = 0;
// find all elements
foreach (string node in Regex.Split(xml,#">\s*<"))
{
// if at end, lower indent
if (Regex.IsMatch(node, #"^\/\w")) indent--;
sb.AppendLine(String.Format("{0}<{1}>", string.Concat(Enumerable.Repeat(tab, indent).ToArray()), node));
// if at start, increase indent
if (Regex.IsMatch(node, #"^<?\w[^>]*[^\/]$")) indent++;
}
// correct first < and last > from the output
String result = sb.ToString().Substring(1);
return result.Remove(result.Length - Environment.NewLine.Length-1);
}