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What is a faster alternative to using document.getElementById('element-id').innerHTML?

I'm making a simple step-by-step wizard for my website which asked viewers questions about their custom order. I've been using JavaScript to replace the content of each "page" with the document.getElementById('element-id').innerHTML command; however, it seems really slow and awkward to add entire divs as a string. For example, some of the code looks something like this:
function loadNextStep() {
document.getElementById('content').innerHTML = 'This is some content.<br>It seems like I need to write everything in one line to make the command work properly.<br><input type="date" id="date-picker" value=""></input>'
}
I'd love to be able to write some multi-line html code, and say "replace everything with this new html."
Is there a faster way of doing the same thing?
Thank you again!

I don't think getElementById or querySelector will make any difference, since the heavier stuff is done when you add a bunch of html elements as a string despite the fact that innerHTML can be vulnerable to cross site scripting if the output of that string has user input commands in it.
But if you still want to do this way you can do by using `` backticks to add as many lines as you'd like.
However, the way I would do is to create those elements on a different function and then output them to your loadNextStep function, then adding to your #content element using the appendChild method.
Here's a quick example of I would do:
function loadNextStep() {
var content = document.getElementById('content');
var step = step1();
step.forEach( stepContent => {
content.appendChild( stepContent );
})
}
function step1() {
var someContent = document.createElement('span');
someContent.innerText = `This is some content. It seems like I need to write everything in one line to make the command work properly.
Yes, but if you use backticks you can have multiple lines.`;
var input = document.createElement('input');
input.type = 'date';
input.id = 'date-picker';
return [ someContent, input ]
}
loadNextStep();
<div id="content">
</div>

How to replace text between two XML tags using jQuery or JavaScript?

I have a XML mark-up/code like the following. I want to replace the text inside one of the tags (in this case <begin>...</begin>) using JavaScript or jQuery.
<part>
<begin>A new beginning</begin>
<framework>Stuff here...</framework>
</part>
The source is inside a textarea. I have the following code, but it is obviously not doing what I want.
code=$("xml-code").val(); // content of XML source
newBegin = "The same old beginning"; // new text inside <begin> tags
newBegin = "<begin>"+newBegin +"</begin>";
code=code.replace("<begin>",newBegin); // replace content
This is just appending to the existing text inside the begin tags. I have a feeling this can be done only using Regex, but unfortunately I have no idea how to do it.

You can use the parseXML() jQuery function, then just replace the appropriate node with .find()/.text()
var s = "<part><begin>A new beginning</begin><framework>Stuff here...</framework></part>";
var xmlDoc = $($.parseXML(s));
xmlDoc.find('begin').text('New beginning');
alert(xmlDoc.text());
http://jsfiddle.net/x3aJc/

Similar to the other answer, using the $.parseXML() function, you could do this:
var xml = $.parseXML($("xml-code").val());
xml.find('begin').text('The same old beginning');
Note that there is no need to replace a whole node, just change it's text. Also, this works if there are multiple <begin> nodes that need the text as well.

You can user regular expression but better dont do it. Use DOM parsers.
var code = $('xml-code').html(); // content of XML source
var newBegin = "The same old beginning"; // new text inside <begin> tags
var regexp = new Regexp('(<part>)[^~]*(<\/part>)', i);
code = code.replace(regexp, '$1' + newBegin + '$2');

Efficiently replacing strings within an HTML block in Javascript

I am using Javascript(with Mootools) to dynamically build a large page using HTML "template" elements, copying the same template many times to populate the page. Within each template I use string keywords that need to be replaced to create the unique IDs. I'm having serious performance issues however in that it takes multiple seconds to perform all these replacements, especially in IE. The code looks like this:
var fieldTemplate = $$('.fieldTemplate')[0];
var fieldTr = fieldTemplate.clone(true, true);
fieldTr.removeClass('fieldTemplate');
replaceIdsHelper(fieldTr, ':FIELD_NODE_ID:', fieldNodeId);
parentTable.grab(fieldTr);
replaceIdsHelper() is the problem method according to IE9's profiler. I've tried two implementations of this method:
// Retrieve the entire HTML body of the element, replace the string and set the HTML back.
var html = rootElem.get('html').replace(new RegExp(replaceStr, 'g'), id);
rootElem.set('html', html);
and
// Load the child elements and replace just their IDs selectively
rootElem.getElements('*').each(function(elem) {
var elemId = elem.get('id');
if (elemId != null) elemId = elemId.replace(replaceStr, id);
elem.set('id', elemId)
});
However, both of these approaches are extremely slow given how many times this method gets called(about 200...). Everything else runs fine, it's only replacing these IDs which seems to be a major performance bottleneck. Does anyone know if there's a way to do this efficiently, or a reason it might be running so slow? The elements start hidden and aren't grabbed by the DOM until after they're created so there's no redrawing happening.
By the way, the reason I'm building the page this way is to keep the code clean, since we need to be able to create new elements dynamically after loading as well. Doing this from the server side would make things much more complicated.

I'm not 100% sure, but it sounds to me that the problem is with the indexing of the dom tree.
First of all, do you must use ids or can you manage with classes? since you say that the replacement of the id is the main issue.
Also, why do you clone part of the dom tree instead of just inserting a new html?
You can use the substitute method of String (when using MooTools), like so:
var template = '<div id="{ID}" class="{CLASSES}">{CONTENT}</div>';
template.substitute({ID: "id1", CLASSES: "c1 c2", CONTENT: "this is the content" });
you can read more about it here http://mootools.net/docs/core/Types/String#String:substitute
Then, just take that string and put it as html inside a container, let's say:
$("container_id").set("html", template);
I think that it might improve the efficiency since it does not clone and then index it again, but I can't be sure. give it a go and see what happens.

there are some things you can do to optimise it - and what #nizan tomer said is very good, the pseudo templating is a good pattern.
First of all.
var fieldTemplate = $$('.fieldTemplate')[0];
var fieldTr = fieldTemplate.clone(true, true);
you should do this as:
var templateHTML = somenode.getElement(".fieldTemplate").get("html"); // no need to clone it.
the template itself should/can be like suggested, eg:
<td id="{id}">{something}</td>
only read it once, no need to clone it for every item - instead, use the new Element constructor and just set the innerHTML - notice it lacks the <tr> </tr>.
if you have an object with data, eg:
var rows = [{
id: "row1",
something: "hello"
}, {
id: "row2",
something: "there"
}];
Array.each(function(obj, index) {
var newel = new Element("tr", {
html: templateHTML.substitute(obj)
});
// defer the inject so it's non-blocking of the UI thread:
newel.inject.delay(10, newel, parentTable);
// if you need to know when done, use a counter + index
// in a function and fire a ready.
});
alternatively, use document fragments:
Element.implement({
docFragment: function(){
return document.createDocumentFragment();
}
});
(function() {
var fragment = Element.docFragment();
Array.each(function(obj) {
fragment.appendChild(new Element("tr", {
html: templateHTML.substitute(obj)
}));
});
// inject all in one go, single dom access
parentTable.appendChild(fragment);
})();
I did a jsperf test on both of these methods:
http://jsperf.com/inject-vs-fragment-in-mootools
surprising win by chrome by a HUGE margin vs firefox and ie9. also surprising, in firefox individual injects are faster than fragments. perhaps the bottleneck is that it's TRs in a table, which has always been dodgy.
For templating: you can also look at using something like mustache or underscore.js templates.

Is there a way to convert HTML into normal text without actually write it to a selector with Jquery?

I understand so far that in Jquery, with html() function, we can convert HTML into text, for example,
$("#myDiv").html(result);
converts "result" (which is the html code) into normal text and display it in myDiv.
Now, my question is, is there a way I can simply convert the html and put it into a variable?
for example:
var temp;
temp = html(result);
something like this, of course this does not work, but how can I put the converted into a variable without write it to the screen? Since I'm checking the converted in a loop, thought it's quite and waste of resource if keep writing it to the screen for every single loop.
Edit:
Sorry for the confusion, for example, if result is " <p>abc</p> " then $(#mydiv).html(result) makes mydiv display "abc", which "converts" html into normal text by removing the <p> tags. So how can I put "abc" into a variable without doing something like var temp=$(#mydiv).text()?

Here is no-jQuery solution:
function htmlToText(html) {
var temp = document.createElement('div');
temp.innerHTML = html;
return temp.textContent; // Or return temp.innerText if you need to return only visible text. It's slower.
}
Works great in IE ≥9.

No, the html method doesn't turn HTML code into text, it turns HTML code into DOM elements. The browser will parse the HTML code and create elements from it.
You don't have to put the HTML code into the page to have it parsed into elements, you can do that in an independent element:
var d = $('<div>').html(result);
Now you have a jQuery object that contains a div element that has the elements from the parsed HTML code as children. Or:
var d = $(result);
Now you have a jQuery object that contains the elements from the parsed HTML code.

You could simply strip all HTML tags:
var text = html.replace(/(<([^>]+)>)/g, "");

Why not use .text()
$("#myDiv").html($(result).text());

you can try:
var tmp = $("<div>").attr("style","display:none");
var html_text = tmp.html(result).text();
tmp.remove();
But the way with modifying string with regular expression is simpler, because it doesn't use DOM traversal.
You may replace html to text string with regexp like in answer of user Crozin.
P.S.
Also you may like the way when <br> is replacing with newline-symbols:
var text = html.replace(/<\s*br[^>]?>/,'\n')
.replace(/(<([^>]+)>)/g, "");

var temp = $(your_selector).html();
the variable temp is a string containing the HTML

$("#myDiv").html(result); is not formatting text into html code. You can use .html() to do a couple of things.
if you say $("#myDiv").html(); where you are not passing in parameters to the `html()' function then you are "GETTING" the html that is currently in that div element.
so you could say,
var whatsInThisDiv = $("#myDiv").html();
console.log(whatsInThisDiv); //will print whatever is nested inside of <div id="myDiv"></div>
if you pass in a parameter with your .html() call you will be setting the html to what is stored inside the variable or string you pass. For instance
var htmlToReplaceCurrent = '<div id="childOfmyDiv">Hi! Im a child.</div>';
$("#myDiv").html(htmlToReplaceCurrent);
That will leave your dom looking like this...
<div id="myDiv">
<div id="childOfmyDiv">Hi! Im a child.</div>
</div>

Easiest, safe solution - use Dom Parser
For more advanced usage - I suggest you try Dompurify
It's cross-browser (and supports Node js). only 19kb gziped
Here is a fiddle I've created that converts HTML to text
const dirty = "Hello <script>in script<\/script> <b>world</b><p> Many other <br/>tags are stripped</p>";
const config = { ALLOWED_TAGS: [''], KEEP_CONTENT: true, USE_PROFILES: { html: true } };
// Clean HTML string and write into the div
const clean = DOMPurify.sanitize(dirty, config);
document.getElementById('sanitized').innerText = clean;
Input: Hello <script>in script<\/script> <b>world</b><p> Many other <br/>tags are stripped</p>
Output: Hello world Many other tags are stripped

Using the dom has several disadvantages. The one not mentioned in the other answers: Media will be loaded, causing network traffic.
I recommend using a regular expression to remove the tags after replacing certain tags like br, p, ol, ul, and headers into \n newlines.

Insert innerHTML with Prototypejs

Say I have a list like this:
<ul id='dom_a'>
<li>foo</li>
</ul>
I know how to insert elements in the ul tag with:
Element.insert('dom_a', {bottom:"<li>bar</li>"});
Since the string I receive contains the dom id, I need to insert the inner HTML instead of the whole element. I need a function to do this:
insert_content('dom_a', {bottom:"<ul id='dom_a'><li>bar</li></ul>"});
And obtain:
<ul id='dom_a'>
<li>foo</li>
<li>bar</li>
</ul>
How should I do this with Prototype ?
Here is the solution I have come up with, can anyone make this better ?
Zena.insert_inner = function(dom, position, content) {
dom = $(dom);
position = position.toLowerCase();
content = Object.toHTML(content);
var elem = new Element('div');
elem.innerHTML = content; // strip scripts ?
elem = elem.down();
var insertions = {};
$A(elem.childElements()).each(function(e) {
insertions[position] = e;
dom.insert(insertions);
});
}

I think you could parse the code block in your variable, then ask it for its innerHTML, and then use insert to stick that at the bottom of the actual node in the DOM.
That might look like this:
var rep_struct = "<ul id='dom_a'><li>bar</li></ul>";
var dummy_node = new Element('div'); // So we can easily access the structure
dummy_node.update(rep_struct);
$('dom_a').insert({bottom: dummy_node.childNodes[0].innerHTML});

I think you can slim down the code a bit by simply appending the innerHTML of the first child of temporary element:
Zena.insert_inner = function(dom, position, content) {
var d = document.createElement('div');
d.innerHTML = content;
var insertions = {};
insertions[position] = d.firstChild.innerHTML;
Element.insert(dom, insertions);
}
Not too much of an improvement though, example here.

I've been looking into the Prototype Documentation and I found this: update function.
By the way you described it, you could use the update function in order to find the current bottom content and then update it (just like innerHTML) by adding the desired code plus the previous stored code.

You could use regular expression to strip the outer element.
Element.Methods.insert_content = function(element, insertions) {
var regex = /^<(\w+)[^>]*>(.*)<\/\1>/;
for (key in insertions) {
insertions[key] = regex.exec(insertions[key])[2];
}
Element.insert(element, insertions);
};
Element.addMethods();
$('dom_a').insert_content({bottom:"<ul id='dom_a'><li>bar</li></ul>"});

If you are using PrototypeJS, you might also want to add script.aculo.us to your project. Builder in script.aculo.us provides a nice way to build complex DOM structures like so:
var myList = Builder.node("ul", {
id: "dom_a"
},[
Builder.node("li", "foo"),
Builder.node("li", "bar"),
]);
After this, you can insert this object which should be rendered as HTML anywhere in the DOM with any insert/update functions (of PrototypeJS) or even standard JavaScript appendChild.
$("my_div").insert({After: myList});
Note that in PrototypeJS insert comes in 4 different modes: After, Before, Top and Bottom. If you use insert without specifying a "mode" as above, the default will be Bottom. That is, the new DOM code will be appended below existing contents of the container element as innerHTML. Top will do the same thing but add it on top of the existing contents. Before and After are also cool ways to append to the DOM. If you use these, the content will be added in the DOM structure before and after the container element, not inside as innerHTML.
With Builder however, there is one thing to keep in mind, .. okay two things really:
i. You cannot enter raw HTML in the object as content... This will fail:
Builder.node("ul", "<li>foo</li>");
ii. When you specify node attributes, keep in mind that you must use className to signify HTML attribute class (and possibly also htmlFor for for attribute... although for attribute seems to be deprecated in HTML5(?), but who does not want to use it for labels)
Builder.node("ul", {
id: "dom_a",
className: "classy_list"
});
I know you are scratching your head because of point i. > What, no raw HTML, dang!
Not to worry. If you still need to add content which might contain HTML inside a Builder created DOM, just do it in the second stage using the insert({Before/After/Top/Bottom: string}). But why'd you want to do it in the first place? It would be really good practice if you wrote an once for all function that generates all kinds of DOM elements rather than stitching in all sorts of strings. The former approach would be neat and elegant. This is something like the inline style versus class type of question. Good design should after all separate content from meta content, or formatting markup / markdown.
One last thing to keep handy in your toolbox is Protype's DOM traversal in case you want to dynamically insert and delete content like a HTML Houdini. Check out the Element next, up, down, previous methods. Besides the $$ is also kinda fun to use, particularly if you know CSS3 selectors.