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Format color while typing in textarea or pre

I'm trying to create a comments section that lets users #someone. When the user types #random and then space, I want it to be highlighted. So I've created something that searches and replaces the string, but I then when the html is replaced, it places the cursor at the beginning. Any way to solve this? Any other way of doing something like this?
$('#textarea').keyup(function() {
txt = this.innerText.split(" ")
new_txt = this.innerText
for (var i = txt.length - 1; i >= 0; i--) {
if (txt[i].startsWith('#') == false) {
delete txt[i]
}
}
txt = txt.sort().join(" ").trim().split(" ")
console.log(txt)
if (txt.length > 0 && txt[0] != "") {
for (var i = 0; i < txt.length; i++) {
new_txt = new_txt.replace(txt[i], '<mark>' + txt[i] + '</mark>')
}
$('#my_console_log').text(new_txt)
this.innerHTML = new_txt
}
});
pre {
border: solid black 1px;
}
mark {
background: blue;
color: red;
}
<script src="https://code.jquery.com/jquery-1.10.2.js"></script>
<title>Test page</title>
<form>
<pre id='textarea' contentEditable='true'></pre>
<div id="my_console_log"></div>
</form>

Here is a simple plugin available which can be useful to you,
Download the plugin and edit the file jquery.hashtags.js and remove the condition for #. You can also change the style as per your requirement.
(function($) {
$.fn.hashtags = function() {
$(this).wrap('<div class="jqueryHashtags"><div class="highlighter"></div></div>').unwrap().before('<div class="highlighter"></div>').wrap('<div class="typehead"></div></div>');
$(this).addClass("theSelector");
autosize($(this));
$(this).on("keyup", function() {
var str = $(this).val();
$(this).parent().parent().find(".highlighter").css("width",$(this).css("width"));
str = str.replace(/\n/g, '<br>');
if(!str.match(/(http|ftp|https):\/\/[\w-]+(\.[\w-]+)+([\w.,#?^=%&:\/~+#-]*[\w#?^=%&\/~+#-])?#([a-zA-Z0-9]+)/g) && !str.match(/(http|ftp|https):\/\/[\w-]+(\.[\w-]+)+([\w.,#?^=%&:\/~+#-]*[\w#?^=%&\/~+#-])?#([a-zA-Z0-9]+)/g) && !str.match(/(http|ftp|https):\/\/[\w-]+(\.[\w-]+)+([\w.,#?^=%&:\/~+#-]*[\w#?^=%&\/~+#-])?#([\u0600-\u06FF]+)/g) && !str.match(/(http|ftp|https):\/\/[\w-]+(\.[\w-]+)+([\w.,#?^=%&:\/~+#-]*[\w#?^=%&\/~+#-])?#([\u0600-\u06FF]+)/g)) {
// Remove below condition for hashtag.
if(!str.match(/#(([_a-zA-Z0-9]+)|([\u0600-\u06FF]+)|([ㄱ-ㅎㅏ-ㅣ가-힣]+)|([ぁ-んァ-ン]+)|([一-龯]+))#/g)) { //arabic support, CJK support
str = str.replace(/#(([_a-zA-Z0-9]+)|([\u0600-\u06FF]+)|([ㄱ-ㅎㅏ-ㅣ가-힣]+)|([ぁ-んァ-ン]+)|([一-龯]+))/g,'<span class="hashtag">#$1</span>');
}else{
str = str.replace(/#(([_a-zA-Z0-9]+)|([\u0600-\u06FF]+)|([ㄱ-ㅎㅏ-ㅣ가-힣]+)|([ぁ-んァ-ン]+)|([一-龯]+))#(([_a-zA-Z0-9]+)|([\u0600-\u06FF]+)|([ㄱ-ㅎㅏ-ㅣ가-힣]+)|([ぁ-んァ-ン]+)|([一-龯]+))/g,'<span class="hashtag">#$1</span>');
}
// Keep this condition.
if(!str.match(/#(([a-zA-Z0-9]+)|([\u0600-\u06FF]+)|([ㄱ-ㅎㅏ-ㅣ가-힣]+)|([ぁ-んァ-ン]+)|([一-龯]+))#/g)) {
str = str.replace(/#(([a-zA-Z0-9]+)|([\u0600-\u06FF]+)|([ㄱ-ㅎㅏ-ㅣ가-힣]+)|([ぁ-んァ-ン]+)|([一-龯]+))/g,'<span class="hashtag">#$1</span>');
}else{
str = str.replace(/#(([a-zA-Z0-9]+)|([\u0600-\u06FF]+)|([ㄱ-ㅎㅏ-ㅣ가-힣]+)|([ぁ-んァ-ン]+)|([一-龯]+))#(([a-zA-Z0-9]+)|([\u0600-\u06FF]+)|([ㄱ-ㅎㅏ-ㅣ가-힣]+)|([ぁ-んァ-ン]+)|([一-龯]+))/g,'<span class="hashtag">#$1</span>');
}
}
$(this).parent().parent().find(".highlighter").html(str);
});
$(this).parent().prev().on('click', function() {
$(this).parent().find(".theSelector").focus();
});
};
})(jQuery);

Instead of replacing the html just append a class with the color that you want

Combination filters + quick search with Isotope

I’m trying to combine two Isotope filtering features (combination filtering via checkbox and quick search) with no luck. My attempt is here: https://codepen.io/anon/pen/WJvmaj, which is a combination of both of the mentioned feature's demos.
At the moment the search is set to return searchResult and checkboxResult, the latter of which isn’t being defined properly in the code I can tell, and there lies my problem: I’m not sure what to set the checkboxResult variable to in order for it to target what’s being returned by the checkbox filtering.

Check if the element includes the text that input in search input or not with .includes() and if the element has any of selected class from checkboxs' value.
BTW, next time please provide a Minimal, Complete, and Verifiable example that demonstrates the problem, not a link to your fiddle or codepen, cause the links would be broken and other users couldn't understand what you asked and the scenario of the question.
$container.isotope({
filter: function() {
var $this = $(this)
var checkText = text == '' ? true : $this.text().includes(text)
var checkClass = inclusives.length == 0 ? true : false;
$.each(inclusives, function(index, c) {
var _class = $this.hasClass(c)
if (_class) {
checkClass = true;
return;
}
})
return checkText && checkClass
}
})
// quick search regex
var qsRegex;
var checkboxFilter;
// templating
var colors = ['red', 'green', 'blue', 'orange'];
var sizes = ['small', 'medium', 'large'];
var prices = [10, 20, 30];
createItems();
// init Isotope
var $container = $('#container')
var $output = $('#output');
// filter with selects and checkboxes
var $checkboxes = $('#form-ui input');
function createItems() {
var $items;
// loop over colors, sizes, prices
// create one item for each
for (var i = 0; i < colors.length; i++) {
for (var j = 0; j < sizes.length; j++) {
for (var k = 0; k < prices.length; k++) {
var color = colors[i];
var size = sizes[j];
var price = prices[k];
var $item = $('<div />', {
'class': 'item ' + color + ' ' + size + ' price' + price
});
$item.append('<p>' + size + '</p><p>$' + price + '</p>');
// add to items
$items = $items ? $items.add($item) : $item;
}
}
}
$items.appendTo($('#container'));
}
var $quicksearch = $('#quicksearch')
// debounce so filtering doesn't happen every millisecond
function debounce(fn, threshold) {
var timeout;
threshold = threshold || 100;
return function debounced() {
clearTimeout(timeout);
var args = arguments;
var _this = this;
function delayed() {
fn.apply(_this, args);
}
timeout = setTimeout(delayed, threshold);
};
}
function Filter() {
// map input values to an array
var inclusives = [];
// inclusive filters from checkboxes
$checkboxes.each(function(i, elem) {
// if checkbox, use value if checked
if (elem.checked) {
inclusives.push(elem.value);
}
});
// combine inclusive filters
var filterValue = inclusives.length ? inclusives.join(', ') : '*';
var text = $quicksearch.val()
$container.isotope({
filter: function() {
var $this = $(this)
var checkText = text == '' ? true : $this.text().includes(text)
var checkClass = inclusives.length == 0 ? true : false;
$.each(inclusives, function(index, c) {
var _class = $this.hasClass(c)
if (_class) {
checkClass = true;
return;
}
})
return checkText && checkClass
}
})
$output.text(filterValue);
}
$quicksearch.on('input', debounce(function() {
Filter()
}));
$checkboxes.change(function() {
Filter()
});
* {
box-sizing: border-box;
}
body {
font-family: sans-serif;
}
.item {
width: 100px;
height: 100px;
float: left;
margin: 5px;
padding: 5px;
}
.item p {
margin: 0;
}
.red {
background: #F33;
}
.blue {
background: #88F;
}
.green {
background: #3A3;
}
.orange {
background: orange;
}
select,
label,
input {
font-size: 20px;
}
label {
margin-right: 10px;
}
#quicksearch {
height: 30px !important;
}
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<script src="//npmcdn.com/isotope-layout#3/dist/isotope.pkgd.js"></script>
<p><input type="text" id="quicksearch" placeholder="Search" /></p>
<div id="form-ui">
<p>
<label><input type="checkbox" value="red" /> red</label>
<label><input type="checkbox" value="green" /> green</label>
<label><input type="checkbox" value="blue" /> blue</label>
<label><input type="checkbox" value="orange" /> orange</label>
</p>
<p id="output">--</p>
</div>
<div id="container">
<!-- items added with JS -->
</div>

How to add CSS styles via JavaScript at runtime? [duplicate]

I need to create a CSS stylesheet class dynamically in JavaScript and assign it to some HTML elements like - div, table, span, tr, etc and to some controls like asp:Textbox, Dropdownlist and datalist.
Is it possible?
It would be nice with a sample.

Here is an option:
var style = document.createElement('style');
style.type = 'text/css';
style.innerHTML = '.cssClass { color: #f00; }';
document.getElementsByTagName('head')[0].appendChild(style);
document.getElementById('someElementId').className = 'cssClass';
<div id="someElementId">test text</div>

Found a better solution, which works across all browsers.
Uses document.styleSheet to add or replace rules. Accepted answer is short and handy but this works across IE8 and less too.
function createCSSSelector (selector, style) {
if (!document.styleSheets) return;
if (document.getElementsByTagName('head').length == 0) return;
var styleSheet,mediaType;
if (document.styleSheets.length > 0) {
for (var i = 0, l = document.styleSheets.length; i < l; i++) {
if (document.styleSheets[i].disabled)
continue;
var media = document.styleSheets[i].media;
mediaType = typeof media;
if (mediaType === 'string') {
if (media === '' || (media.indexOf('screen') !== -1)) {
styleSheet = document.styleSheets[i];
}
}
else if (mediaType=='object') {
if (media.mediaText === '' || (media.mediaText.indexOf('screen') !== -1)) {
styleSheet = document.styleSheets[i];
}
}
if (typeof styleSheet !== 'undefined')
break;
}
}
if (typeof styleSheet === 'undefined') {
var styleSheetElement = document.createElement('style');
styleSheetElement.type = 'text/css';
document.getElementsByTagName('head')[0].appendChild(styleSheetElement);
for (i = 0; i < document.styleSheets.length; i++) {
if (document.styleSheets[i].disabled) {
continue;
}
styleSheet = document.styleSheets[i];
}
mediaType = typeof styleSheet.media;
}
if (mediaType === 'string') {
for (var i = 0, l = styleSheet.rules.length; i < l; i++) {
if(styleSheet.rules[i].selectorText && styleSheet.rules[i].selectorText.toLowerCase()==selector.toLowerCase()) {
styleSheet.rules[i].style.cssText = style;
return;
}
}
styleSheet.addRule(selector,style);
}
else if (mediaType === 'object') {
var styleSheetLength = (styleSheet.cssRules) ? styleSheet.cssRules.length : 0;
for (var i = 0; i < styleSheetLength; i++) {
if (styleSheet.cssRules[i].selectorText && styleSheet.cssRules[i].selectorText.toLowerCase() == selector.toLowerCase()) {
styleSheet.cssRules[i].style.cssText = style;
return;
}
}
styleSheet.insertRule(selector + '{' + style + '}', styleSheetLength);
}
}
Function is used as follows.
createCSSSelector('.mycssclass', 'display:none');

Short answer, this is compatible "on all browsers" (specifically, IE8/7):
function createClass(name,rules){
var style = document.createElement('style');
style.type = 'text/css';
document.getElementsByTagName('head')[0].appendChild(style);
if(!(style.sheet||{}).insertRule)
(style.styleSheet || style.sheet).addRule(name, rules);
else
style.sheet.insertRule(name+"{"+rules+"}",0);
}
createClass('.whatever',"background-color: green;");
And this final bit applies the class to an element:
function applyClass(name,element,doRemove){
if(typeof element.valueOf() == "string"){
element = document.getElementById(element);
}
if(!element) return;
if(doRemove){
element.className = element.className.replace(new RegExp("\\b" + name + "\\b","g"));
}else{
element.className = element.className + " " + name;
}
}
Here's a little test page as well: https://gist.github.com/shadybones/9816763
The key little bit is the fact that style elements have a "styleSheet"/"sheet" property which you can use to to add/remove rules on.

There is a light jQuery plugin which allows to generate CSS declarations: jQuery-injectCSS
In fact, it uses JSS (CSS described by JSON), but it's quite easy to handle in order to generate dynamic css stylesheets.
$.injectCSS({
"#test": {
height: 123
}
});

YUI has by far the best stylesheet utility I have seen out there. I encourage you to check it out, but here's a taste:
// style element or locally sourced link element
var sheet = YAHOO.util.StyleSheet(YAHOO.util.Selector.query('style',null,true));
sheet = YAHOO.util.StyleSheet(YAHOO.util.Dom.get('local'));
// OR the id of a style element or locally sourced link element
sheet = YAHOO.util.StyleSheet('local');
// OR string of css text
var css = ".moduleX .alert { background: #fcc; font-weight: bold; } " +
".moduleX .warn { background: #eec; } " +
".hide_messages .moduleX .alert, " +
".hide_messages .moduleX .warn { display: none; }";
sheet = new YAHOO.util.StyleSheet(css);
There are obviously other much simpler ways of changing styles on the fly such as those suggested here. If they make sense for your problem, they might be best, but there are definitely reasons why modifying CSS is a better solution. The most obvious case is when you need to modify a large number of elements. The other major case is if you need your style changes to involve the cascade. Using the DOM to modify an element will always have a higher priority. It's the sledgehammer approach and is equivalent to using the style attribute directly on the HTML element. That is not always the desired effect.

As of IE 9. You can now load a text file and set a style.innerHTML property. So essentially you can now load a css file through ajax (and get the callback) and then just set the text inside of a style tag like this.
This works in other browsers, not sure how far back. But as long as you don't need to support IE8 then it would work.
// RESULT: doesn't work in IE8 and below. Works in IE9 and other browsers.
$(document).ready(function() {
// we want to load the css as a text file and append it with a style.
$.ajax({
url:'myCss.css',
success: function(result) {
var s = document.createElement('style');
s.setAttribute('type', 'text/css');
s.innerHTML = result;
document.getElementsByTagName("head")[0].appendChild(s);
},
fail: function() {
alert('fail');
}
})
});
and then you can have it pull an external file like the myCss.css
.myClass { background:#F00; }

Using google closure:
you can just use the ccsom module:
goog.require('goog.cssom');
var css_node = goog.cssom.addCssText('.cssClass { color: #F00; }');
The javascript code attempts to be cross browser when putting the css node into the document head.

Here is Vishwanath's solution slightly rewritten with comments :
function setStyle(cssRules, aSelector, aStyle){
for(var i = 0; i < cssRules.length; i++) {
if(cssRules[i].selectorText && cssRules[i].selectorText.toLowerCase() == aSelector.toLowerCase()) {
cssRules[i].style.cssText = aStyle;
return true;
}
}
return false;
}
function createCSSSelector(selector, style) {
var doc = document;
var allSS = doc.styleSheets;
if(!allSS) return;
var headElts = doc.getElementsByTagName("head");
if(!headElts.length) return;
var styleSheet, media, iSS = allSS.length; // scope is global in a function
/* 1. search for media == "screen" */
while(iSS){ --iSS;
if(allSS[iSS].disabled) continue; /* dont take into account the disabled stylesheets */
media = allSS[iSS].media;
if(typeof media == "object")
media = media.mediaText;
if(media == "" || media=='all' || media.indexOf("screen") != -1){
styleSheet = allSS[iSS];
iSS = -1; // indication that media=="screen" was found (if not, then iSS==0)
break;
}
}
/* 2. if not found, create one */
if(iSS != -1) {
var styleSheetElement = doc.createElement("style");
styleSheetElement.type = "text/css";
headElts[0].appendChild(styleSheetElement);
styleSheet = doc.styleSheets[allSS.length]; /* take the new stylesheet to add the selector and the style */
}
/* 3. add the selector and style */
switch (typeof styleSheet.media) {
case "string":
if(!setStyle(styleSheet.rules, selector, style));
styleSheet.addRule(selector, style);
break;
case "object":
if(!setStyle(styleSheet.cssRules, selector, style));
styleSheet.insertRule(selector + "{" + style + "}", styleSheet.cssRules.length);
break;
}

One liner, attach one or many new cascading rule(s) to the document.
This example attach a cursor:pointer to every button, input, select.
document.body.appendChild(Object.assign(document.createElement("style"), {textContent: "select, button, input {cursor:pointer}"}))

https://jsfiddle.net/xk6Ut/256/
One option to dynamically create and update CSS class in JavaScript:
Using Style Element to create a CSS section
Using an ID for the style element so that we can update the CSS
class
.....
function writeStyles(styleName, cssText) {
var styleElement = document.getElementById(styleName);
if (styleElement)
document.getElementsByTagName('head')[0].removeChild(
styleElement);
styleElement = document.createElement('style');
styleElement.type = 'text/css';
styleElement.id = styleName;
styleElement.innerHTML = cssText;
document.getElementsByTagName('head')[0].appendChild(styleElement);
}
...
var cssText = '.testDIV{ height:' + height + 'px !important; }';
writeStyles('styles_js', cssText)

An interesting project which could help you out in your task is JSS.
JSS is an authoring tool for CSS which allows you to use JavaScript to describe styles in a declarative, conflict-free and reusable way. It can compile in the browser, server-side or at build time in Node.
JSS library allows you to inject in the DOM/head section using the .attach() function.
Repl online version for evaluation.
Further information on JSS.
An example:
// Use plugins.
jss.use(camelCase())
// Create your style.
const style = {
myButton: {
color: 'green'
}
}
// Compile styles, apply plugins.
const sheet = jss.createStyleSheet(style)
// If you want to render on the client, insert it into DOM.
sheet.attach()

I was looking through some of the answers here, and I couldn't find anything that automatically adds a new stylesheet if there are none, and if not simply modifies an existing one that already contains the style needed, so I made a new function (should work accross all browsers, though not tested, uses addRule and besides that only basic native JavaScript, let me know if it works):
function myCSS(data) {
var head = document.head || document.getElementsByTagName("head")[0];
if(head) {
if(data && data.constructor == Object) {
for(var k in data) {
var selector = k;
var rules = data[k];
var allSheets = document.styleSheets;
var cur = null;
var indexOfPossibleRule = null,
indexOfSheet = null;
for(var i = 0; i < allSheets.length; i++) {
indexOfPossibleRule = findIndexOfObjPropInArray("selectorText",selector,allSheets[i].cssRules);
if(indexOfPossibleRule != null) {
indexOfSheet = i;
break;
}
}
var ruleToEdit = null;
if(indexOfSheet != null) {
ruleToEdit = allSheets[indexOfSheet].cssRules[indexOfPossibleRule];
} else {
cur = document.createElement("style");
cur.type = "text/css";
head.appendChild(cur);
cur.sheet.addRule(selector,"");
ruleToEdit = cur.sheet.cssRules[0];
console.log("NOPE, but here's a new one:", cur);
}
applyCustomCSSruleListToExistingCSSruleList(rules, ruleToEdit, (err) => {
if(err) {
console.log(err);
} else {
console.log("successfully added ", rules, " to ", ruleToEdit);
}
});
}
} else {
console.log("provide one paramter as an object containing the cssStyles, like: {\"#myID\":{position:\"absolute\"}, \".myClass\":{background:\"red\"}}, etc...");
}
} else {
console.log("run this after the page loads");
}
};
then just add these 2 helper functions either inside the above function, or anywhere else:
function applyCustomCSSruleListToExistingCSSruleList(customRuleList, existingRuleList, cb) {
var err = null;
console.log("trying to apply ", customRuleList, " to ", existingRuleList);
if(customRuleList && customRuleList.constructor == Object && existingRuleList && existingRuleList.constructor == CSSStyleRule) {
for(var k in customRuleList) {
existingRuleList["style"][k] = customRuleList[k];
}
} else {
err = ("provide first argument as an object containing the selectors for the keys, and the second argument is the CSSRuleList to modify");
}
if(cb) {
cb(err);
}
}
function findIndexOfObjPropInArray(objPropKey, objPropValue, arr) {
var index = null;
for(var i = 0; i < arr.length; i++) {
if(arr[i][objPropKey] == objPropValue) {
index = i;
break;
}
}
return index;
}
(notice that in both of them I use a for loop instead of .filter, since the CSS style / rule list classes only have a length property, and no .filter method.)
Then to call it:
myCSS({
"#coby": {
position:"absolute",
color:"blue"
},
".myError": {
padding:"4px",
background:"salmon"
}
})
Let me know if it works for your browser or gives an error.

Looked through the answers and the most obvious and straight forward is missing: use document.write() to write out a chunk of CSS you need.
Here is an example (view it on codepen: http://codepen.io/ssh33/pen/zGjWga):
<style>
#import url(http://fonts.googleapis.com/css?family=Open+Sans:800);
.d, body{ font: 3vw 'Open Sans'; padding-top: 1em; }
.d {
text-align: center; background: #aaf;
margin: auto; color: #fff; overflow: hidden;
width: 12em; height: 5em;
}
</style>
<script>
function w(s){document.write(s)}
w("<style>.long-shadow { text-shadow: ");
for(var i=0; i<449; i++) {
if(i!= 0) w(","); w(i+"px "+i+"px #444");
}
w(";}</style>");
</script>
<div class="d">
<div class="long-shadow">Long Shadow<br> Short Code</div>
</div>

For the benefit of searchers; if you are using jQuery, you can do the following:
var currentOverride = $('#customoverridestyles');
if (currentOverride) {
currentOverride.remove();
}
$('body').append("<style id=\"customoverridestyles\">body{background-color:pink;}</style>");
Obviously you can change the inner css to whatever you want.
Appreciate some people prefer pure JavaScript, but it works and has been pretty robust for writing/overwriting styles dynamically.

function createCSSClass(selector, style, hoverstyle)
{
if (!document.styleSheets)
{
return;
}
if (document.getElementsByTagName("head").length == 0)
{
return;
}
var stylesheet;
var mediaType;
if (document.styleSheets.length > 0)
{
for (i = 0; i < document.styleSheets.length; i++)
{
if (document.styleSheets[i].disabled)
{
continue;
}
var media = document.styleSheets[i].media;
mediaType = typeof media;
if (mediaType == "string")
{
if (media == "" || (media.indexOf("screen") != -1))
{
styleSheet = document.styleSheets[i];
}
}
else if (mediaType == "object")
{
if (media.mediaText == "" || (media.mediaText.indexOf("screen") != -1))
{
styleSheet = document.styleSheets[i];
}
}
if (typeof styleSheet != "undefined")
{
break;
}
}
}
if (typeof styleSheet == "undefined") {
var styleSheetElement = document.createElement("style");
styleSheetElement.type = "text/css";
document.getElementsByTagName("head")[0].appendChild(styleSheetElement);
for (i = 0; i < document.styleSheets.length; i++) {
if (document.styleSheets[i].disabled) {
continue;
}
styleSheet = document.styleSheets[i];
}
var media = styleSheet.media;
mediaType = typeof media;
}
if (mediaType == "string") {
for (i = 0; i < styleSheet.rules.length; i++)
{
if (styleSheet.rules[i].selectorText.toLowerCase() == selector.toLowerCase())
{
styleSheet.rules[i].style.cssText = style;
return;
}
}
styleSheet.addRule(selector, style);
}
else if (mediaType == "object")
{
for (i = 0; i < styleSheet.cssRules.length; i++)
{
if (styleSheet.cssRules[i].selectorText.toLowerCase() == selector.toLowerCase())
{
styleSheet.cssRules[i].style.cssText = style;
return;
}
}
if (hoverstyle != null)
{
styleSheet.insertRule(selector + "{" + style + "}", 0);
styleSheet.insertRule(selector + ":hover{" + hoverstyle + "}", 1);
}
else
{
styleSheet.insertRule(selector + "{" + style + "}", 0);
}
}
}
createCSSClass(".modalPopup .header",
" background-color: " + lightest + ";" +
"height: 10%;" +
"color: White;" +
"line-height: 30px;" +
"text-align: center;" +
" width: 100%;" +
"font-weight: bold; ", null);

Here is my modular solution:
var final_style = document.createElement('style');
final_style.type = 'text/css';
function addNewStyle(selector, style){
final_style.innerHTML += selector + '{ ' + style + ' } \n';
};
function submitNewStyle(){
document.getElementsByTagName('head')[0].appendChild(final_style);
final_style = document.createElement('style');
final_style.type = 'text/css';
};
function submitNewStyleWithMedia(mediaSelector){
final_style.innerHTML = '#media(' + mediaSelector + '){\n' + final_style.innerHTML + '\n};';
submitNewStyle();
};
You basically anywhere in your code do:
addNewStyle('body', 'color: ' + color1); , where color1 is defined variable.
When you want to "post" the current CSS file you simply do submitNewStyle(),
and then you can still add more CSS later.
If you want to add it with "media queries", you have the option.
After "addingNewStyles" you simply use submitNewStyleWithMedia('min-width: 1280px');.
It was pretty useful for my use-case, as I was changing CSS of public (not mine) website according to current time. I submit one CSS file before using "active" scripts, and the rest afterwards (makes the site look kinda-like it should before accessing elements through querySelector).

This is what worked for me in Angular:
In HTML I have button with programmatically created CSS with specific ID:
<button [id]="'hoverbutton1'+item.key" [ngClass]="getHoverButtonClass()">
<mat-icon class="icon">open_in_new</mat-icon>
</button>
In typescript I created CSS and assign it to specific element with given ID:
addClasses(){
var style1 = document.createElement('style');
style1.innerHTML = '.hoverbutton'+this.item.key+' { display: none; }';
document.getElementsByTagName('head')[0].appendChild(style1);
}
getHoverButtonClass() {
return "hoverbutton"+this.item.key
}
This way I can create as many CSS classes as I want and assign them to elements individually. :)

How do I supplant jQuery's toggleClass method with pure JavaScript?

How can I turn this piece of jQuery code into JavaScript?
$('#element').click(function(){
$(this).toggleClass('class1 class2')
});
I have already tried the following pieces of code, but to no avail.
First one is:
var element = document.getElementById('element'),
classNum = 0; // Supposing I know that the first time there will be that class
element.onmousedown = function() {
if (classNum === 0) {
this.classList.remove("class1");
this.classList.add("class2");
classNum = 1;
}
else if (classNum === 1) {
this.classList.remove("class2");
this.classList.add("class1");
classNum = 0;
}
}
Second one is:
var element = document.getElementById('element'),
classNum = 0; // Supposing I know that the first time there will be that class
element.onmousedown = function() {
if (classNum === 0) {
this.className -= "class1";
this.classList += "class2";
classNum = 1;
}
else if (classNum === 1) {
this.classList -= "class2";
this.classList += "class1";
classNum = 0;
}
}
Any answer that doesn't suggest that I stick with jQuery will be greatly appreciated.
[EDIT]
I've tried all of your solutions, but haven't been able to get it right. I believe it's because I didn't state clearly that the element has multiple classes like so:
class="class1 class3 class4"
And what I want is basically to replace class1 with class2 and toggle between them.

Update:
In response to comments, classList.toggle is a pure javascript solution. It has nothing to do with jQuery as one comment implies. If there is a requirement to support old versions of IE then there is a shim (pollyfill) at the MDN link below. And this shim, if needed, is far superior to the accepted answer.
Using classList.toggle certainly seems like the simplest solution. Also see Can I Use classList for browser support.
element.onclick = function() {
'class1 class2'.split(' ').forEach(function(s) {
element.classList.toggle(s);
});
}
Run the snippet to try
box.onclick = function() {
'class1 class2'.split(' ').forEach(function(s) {
box.classList.toggle(s);
stdout.innerHTML = box.className;
});
}
/* alternative
box.onclick = function() {
['class1', 'class2'].forEach(function(s) {
box.classList.toggle(s);
stdout.innerHTML = box.className;
});
}
*/
.class1 { background-color: red;}
.class2 { background-color: blue;}
.class3 { width: 100px; height: 100px; border: 1px black solid;}
click me:
<div id="box" class="class1 class3"></div>
<div id="stdout"></div>

classNum is a local variable.
Every time the event handler is called, you get a new variable, which has nothing to do with the value from the last call.
You want that to be a global variable.
Or, better yet, check classList.contains instead.

From: You might not need jQuery
$(el).toggleClass(className);
Is replaced by:
if (el.classList) {
el.classList.toggle(className);
} else {
var classes = el.className.split(' ');
var existingIndex = classes.indexOf(className);
if (existingIndex >= 0)
classes.splice(existingIndex, 1);
else
classes.push(className);
el.className = classes.join(' ');
}
Then simply wrap that function call within a document.getElementById('elementId').click

See fiddle: https://jsfiddle.net/2ch8ztdk/
var s = document.getElementById('element');
s.onclick=function(){
if(s.className == "class1"){
s.className = "class2"
} else {
s.className = "class1"
}
}

Your code is close, but your classNum variable isn't iterative. Try this:
var element = document.getElementById("element");
var numCount = 0;
element.addEventListener('click', function() {
if (numCount === 0) {
this.className = "";
this.className += " class1";
numCount++;
} else {
this.className = "";
this.className += " class2";
numCount = 0;
}
});
.class1 {
color: red;
}
.class2 {
color: blue;
}
<div id="element">click me</div>

you can use classList, but it only support IE 10+
Demo
var eles = document.querySelectorAll('#element');
var classNames = 'one two';
for(var i = 0; i < eles.length; i ++){
eles[i].onclick = function(e){
toggleClass.call(this, classNames);
}
}
function toggleClass(names){
var sp = names.split(' ');
for(var i = 0; i < sp.length; i++){
this.classList.toggle(sp[i]);
}
}

UPDATED MY ANSWER TO SUPPORT MULTIPLE CLASSES PER ELEMENT
https://jsfiddle.net/pwyncL8r/2/ This will now allow the element to already have n classes and still swap only one, retaining the other classes.
HTML
<div id="div1" style="width: 100px; height: 100px;" class="backBlack left100"</div>
<input type="button" id="swapButton" value="Css Swap" />
CSS
.backBlack {
background-color: black;
}
.backRed {
background-color: red;
}
.left100 {
margin-left: 100px;
}
JS
swapButton.onclick = function() {
var curClassIsBlack = (' ' + document.getElementById("div1").className + ' ').indexOf(' backBlack ') > -1
if (curClassIsBlack) {
document.getElementById("div1").className =
document.getElementById("div1").className.replace(/(?:^|\s)backBlack(?!\S)/g, '')
document.getElementById("div1").className += " backRed";
} else {
document.getElementById("div1").className =
document.getElementById("div1").className.replace(/(?:^|\s)backRed(?!\S)/g,'')
document.getElementById("div1").className += " backBlack";
}
}

Wrapping Sentences within <p> Tags with <span>'s, But Keep Other Tags

To give you an idea of what I need, I have been using the below code to parse content within tags and wrap each sentence within tags so I can then interact with sentences on a page.
$('p').each(function() {
var sentences = $(this)
.text()
.replace(/(((?![.!?]['"]?\s).)*[.!?]['"]?)(\s|$)/g,
'<span class="sentence">$1</span>$3');
$(this).html(sentences);
});
However, the following line demonstrates my problem:
<p>This is a link and it is removed with the above code! Here is another sentence.</p>
Nested tags such as <a>, <img> etc...within <p> tags that I'm searching through are removed with the code that I'm using. I need to keep these tags intact, so the content stays the same within the <p> tags.
I need:
<p><span class="sentence">This is a link and it is removed with the above code!</sentence><sentence>Here is another sentence.</sentence></p>
After reading this barn-burner about parsing HTML with regex, I've concluded that I need to use a combo of an HTML parser of some sort to traverse through sub-tags within a <p> tag, and then use a regex to find the sentences. I think the regex I have listed above should work for most of my uses, if that helps.
So: how should I do it?

It is really difficult to tokenise language, reliably, into sentences and that is without the added complexity of throwing html into the equation. There are some applications etc out there that attempt to deal with Natural Language Processing, an example would be the Stanford Tokenizer with runs on Java (not Javascript)
And as people keep mentioning, a regex is not the solution to this problem, language is not regular so don't expect a Regular Expression only solution.
There is a question here on SO, Basic NLP in CoffeeScript or JavaScript — Punkt tokenizaton, simple trained Bayes models — where to start? Which I think summarises things fairly simply for Javascript.
Anyway, to at least give you a little something that you could play with, I knocked up a little code for you. This works reasonable well until the markup/language begins to resemble anything slightly complex or different, but ultimately fails the mark by a long way. But, it may be enough for what you need, I don't know.
CSS
.emphasis {
font-style: italic;
}
.bold {
font-weight: bold;
}
.emphasis.bold {
font-style: italic;
font-weight: bold;
}
.unidentified {
background-color: pink;
}
.sentence0 {
background-color: yellow;
}
.sentence1 {
background-color: green;
}
.sentence2 {
background-color: red;
}
.whitespace {
white-space: pre;
background-color: blue;
}
Javascript
/*jslint maxerr: 50, indent: 4, browser: true */
(function () {
"use strict";
var rxOpen = new RegExp("<[^\\/].+?>"),
rxClose = new RegExp("<\\/.+?>"),
rxWhitespace = new RegExp("^\\s+?"),
rxSupStart = new RegExp("^<sup\\b[^>]*>"),
rxSupEnd = new RegExp("<\/sup>"),
sentenceEnd = [],
color = 0,
rxIndex;
sentenceEnd.push(new RegExp("[^\\d][\\.!\\?]+"));
sentenceEnd.push(new RegExp("(?=([^\\\"]*\\\"[^\\\"]*\\\")*[^\\\"]*?$)"));
sentenceEnd.push(new RegExp("(?![^\\(]*?\\))"));
sentenceEnd.push(new RegExp("(?![^\\[]*?\\])"));
sentenceEnd.push(new RegExp("(?![^\\{]*?\\})"));
sentenceEnd.push(new RegExp("(?![^\\|]*?\\|)"));
//sentenceEnd.push(new RegExp("(?![^\\\\]*?\\\\)"));
//sentenceEnd.push(new RegExp("(?![^\\/.]*\\/)")); // all could be a problem, but this one is problematic
rxIndex = new RegExp(sentenceEnd.reduce(function (previousValue, currentValue) {
return previousValue + currentValue.source;
}, ""));
function indexSentenceEnd(html) {
var index = html.search(rxIndex);
if (index !== -1) {
index += html.match(rxIndex)[0].length - 1;
}
return index;
}
function pushSpan(array, className, string, classNameOpt) {
if (className === "sentence") {
className += color % 2;
if (classNameOpt) {
className += " " + classNameOpt;
}
color += 1;
}
array.push('<span class="' + className + '">' + string + '</span>');
}
function addSupToPrevious(html, array) {
var sup = html.search(rxSupStart),
end = 0,
last;
if (sup !== -1) {
end = html.search(rxSupEnd);
if (end !== -1) {
last = array.pop();
end = end + 6;
array.push(last.slice(0, -7) + html.slice(0, end) + last.slice(-7));
}
}
return html.slice(end);
}
function leadingWhitespaces(html, array) {
var whitespace = html.search(rxWhitespace),
count = 0;
if (whitespace !== -1) {
count = html.match(rxWhitespace)[0].length;
pushSpan(array, "whitespace", html.slice(0, count));
}
return html.slice(count);
}
function paragraphIsSentence(html, array) {
var index = indexSentenceEnd(html);
if (index === -1 || index === html.length) {
pushSpan(array, "sentence", html, "paragraphIsSentence");
html = "";
}
return html;
}
function paragraphNoMarkup(html, array) {
var open = html.search(rxOpen),
index = 0;
if (open === -1) {
index = indexSentenceEnd(html);
if (index === -1) {
index = html.length;
}
pushSpan(array, "sentence", html.slice(0, index += 1), "paragraphNoMarkup");
}
return html.slice(index);
}
function sentenceUncontained(html, array) {
var open = html.search(rxOpen),
index = 0,
close;
if (open !== -1) {
index = indexSentenceEnd(html);
if (index === -1) {
index = html.length;
}
close = html.search(rxClose);
if (index < open || index > close) {
pushSpan(array, "sentence", html.slice(0, index += 1), "sentenceUncontained");
} else {
index = 0;
}
}
return html.slice(index);
}
function sentenceContained(html, array) {
var open = html.search(rxOpen),
index = 0,
close,
count;
if (open !== -1) {
index = indexSentenceEnd(html);
if (index === -1) {
index = html.length;
}
close = html.search(rxClose);
if (index > open && index < close) {
count = html.match(rxClose)[0].length;
pushSpan(array, "sentence", html.slice(0, close + count), "sentenceContained");
index = close + count;
} else {
index = 0;
}
}
return html.slice(index);
}
function anythingElse(html, array) {
pushSpan(array, "sentence2", html, "anythingElse");
return "";
}
function guessSenetences() {
var paragraphs = document.getElementsByTagName("p");
Array.prototype.forEach.call(paragraphs, function (paragraph) {
var html = paragraph.innerHTML,
length = html.length,
array = [],
safety = 100;
while (length && safety) {
html = addSupToPrevious(html, array);
if (html.length === length) {
html = leadingWhitespaces(html, array);
if (html.length === length) {
html = paragraphIsSentence(html, array);
if (html.length === length) {
html = paragraphNoMarkup(html, array);
if (html.length === length) {
html = sentenceUncontained(html, array);
if (html.length === length) {
html = sentenceContained(html, array);
if (html.length === length) {
html = anythingElse(html, array);
}
}
}
}
}
}
length = html.length;
safety -= 1;
}
paragraph.innerHTML = array.join("");
});
}
guessSenetences();
}());
On jsfiddle

you need to use .html() instead of .text() if you want to keep tags intact.
Check below code and let me know if it doesn't work out.
DEMO
$('p').each(function() {
var sentences = $(this)
.html()
.replace(/(((?![.!?]['"]?\s).)*[.!?]['"]?)(\s|$)/g,
'<span class="sentence">$1</span>$3');
$(this).html(sentences);
});