Tutorial by Examples: e

Counter is a dict sub class that allows you to easily count objects. It has utility methods for working with the frequencies of the objects that you are counting. import collections counts = collections.Counter([1,2,3]) the above code creates an object, counts, which has the frequencies of all ...

collections.defaultdict(default_factory) returns a subclass of dict that has a default value for missing keys. The argument should be a function that returns the default value when called with no arguments. If there is nothing passed, it defaults to None. >>> state_capitals = collections.d...

$ git branch -d dev Deletes the branch named dev if its changes are merged with another branch and will not be lost. If the dev branch does contain changes that have not yet been merged that would be lost, git branch -d will fail: $ git branch -d dev error: The branch 'dev' is not fully merged...

The term "IFrame" means Inline Frame. It can be used to include another page in your page. This will yield a small frame which shows the exact contents of the base.html. <iframe src="base.html"></iframe>

The IFrame can be resized using the width and height attributes, where the values are represented in pixels (HTML 4.01 allowed percentage values, but HTML 5 only allows values in CSS pixels). <iframe src="base.html" width="800" height="600"></iframe>

Normally a change of webpage within an Iframe is initiated from with the Iframe, for example, clicking a link inside the Ifame. However, it is possible to change an IFrame's content from outside the IFrame. You can use an anchor tag whose href attribute is set to the desired URL and whose target at...

The srcdoc attribute can be used (instead of the src attribute) to specify the exact contents of the iframe as a whole HTML document. This will yield an IFrame with the text "IFrames are cool!" <iframe srcdoc="<p>IFrames are cool!</p>"></iframe> If the...

jQuery code is often wrapped in jQuery(function($) { ... }); so that it only runs after the DOM has finished loading. <script type="text/javascript"> jQuery(function($) { // this will set the div's text to "Hello". $("#myDiv").text("Hello"...

These are all equivalent, the code inside the blocks will run when the document is ready: $(function() { // code }); $().ready(function() { // code }); $(document).ready(function() { // code }); Because these are equivalent the first is the recommended form, the following is a ...

When a user subscribes to a channel, you may want to set state for that newly subscribed user. While there is a subscribe with state API, there are some scenarios where this is not the most optimal/reliable technique (like during a disconnect/reconnect situation - the state will be lost and not rein...

To remove an element inside an array, e.g. the element with the index 1. $fruit = array("bananas", "apples", "peaches"); unset($fruit[1]); This will remove the apples from the list, but notice that unset does not change the indexes of the remaining elements. So $fr...

Boolean is a type, having two values, denoted as true or false. This code sets the value of $foo as true and $bar as false: $foo = true; $bar = false; true and false are not case sensitive, so TRUE and FALSE can be used as well, even FaLsE is possible. Using lower case is most common and recom...

A cookie is set using the setcookie() function. Since cookies are part of the HTTP header, you must set any cookies before sending any output to the browser. Example: setcookie("user", "Tom", time() + 86400, "/"); // check syntax for function params Description: ...

Retrieve and Output a Cookie Named user The value of a cookie can be retrieved using the global variable $_COOKIE. example if we have a cookie named user we can retrieve it like this echo $_COOKIE['user'];

The value of a cookie can be modified by resetting the cookie setcookie("user", "John", time() + 86400, "/"); // assuming there is a "user" cookie already Cookies are part of the HTTP header, so setcookie() must be called before any output is sent to the...

Use the isset() function upon the superglobal $_COOKIE variable to check if a cookie is set. Example: // PHP <7.0 if (isset($_COOKIE['user'])) { // true, cookie is set echo 'User is ' . $_COOKIE['user']; else { // false, cookie is not set echo 'User is not logged in'; } ...

cat < file.txt Output is same as cat file.txt, but it reads the contents of the file from standard input instead of directly from the file. printf "first line\nSecond line\n" | cat -n The echo command before | outputs two lines. The cat command acts on the output to add line num...

# Length of a string $ var='12345' $ echo "${#var}" 5 Note that it's the length in number of characters which is not necessarily the same as the number of bytes (like in UTF-8 where most characters are encoded in more than one byte), nor the number of glyphs/graphemes (some of which ...

One of the most common tasks is retrieving an existing element from the DOM to manipulate. Most commonly these methods are executed on document, because it is the root node, but all these methods work on any HTML element in the tree. They will only return children from the node it is executed on. R...

An element can be cloned by invoking the cloneNode method on it. If the first parameter passed to cloneNode is true, the children of the original will also be cloned. var original = document.getElementsByTagName("li")[0]; var clone = original.cloneNode(true);