it has to be taken as a postulate

you've mentioned the word theory a lot of times. How can we test this?

Regular Expression Functions There are three regular-expression functions that operate on strings: matches() tests if a regular expression matches a string. replace() uses regular expressions to replace portions of a string. tokenize() returns a sequence of strings formed by breaking a supplied input string at any separator that matches a given regular expression. Example:   

What’s the difference between xsl:value-of, xsl:copy-of, and xsl:sequence? xsl:value-of always creates a text node. xsl:copy-of always creates a copy. xsl:sequence returns the nodes selected, subject possibly to atomization. Sequences can be extended with xsl:sequence.

<xsl:variable name="date" select="xs:date('2003-11-20')"/>

Types XSLT 2.0 allows you to declare: The type of variables. The return type of templates. The type of sequences (constructed with xsl:sequence) The return type of (user-declared) functions. Both the type and required type of parameters.

 <xsl:sequence select="1 to 16"/>

<xsl:for-each select="1 to 32">  <!-- Do something useful here --></xsl:for-each>

The new as attribute defines the data type of the variable, and the asterisk (xs:integer*) means that the sequence contains zero or more integers

One of the major new concepts in XPath 2.0 and XSLT 2.0 is that everything is a sequence.

What is a Function Expression?A JavaScript function can also be defined using an expression.A function expression can be stored in a variable:var x = function (a, b) {return a * b};After a function expression has been stored in a variable, the variable can be used as a function. Functions stored in variables do not need function names. They are always invoked (called) using the variable name.

Writing an async function is quite simple. You just need to add the async keyword prior to function:

Our Promise can have one of three states:

Using objects as keys is one of most notable and important Map features.

Map is a collection of keyed data items, just like an Object. But the main difference is that Map allows keys of any type.

he basic syntax is: let promise = fetch(url, [options])

Webpack is a most have to compile a complete JavaScript project.

linter

This tool accepts both a configuration file and line parameters.

Here are the possible ways to make an API call:XMLHttpRequestfetchAxiosjQuery

document.addEventListener(event, function, useCapture)

It should be 48x48 pixels.

It is an unordered set of name/value pairs.

Square brackets hold arrays and values are separated by ,(comma).

JSON syntax is basically considered as a subset of JavaScript syntax;

name/value pairs.

Extensions for Firefox are built using the WebExtensions APIs, a cross-browser system for developing extensions.

The most interesting key here is content_scripts, which tells Firefox to load a script into

description is optional, but recommended: it's displayed in the Add-ons Manager. icons is optional, but recommended: it allows you to specify an icon for the extension, that will be shown in the Add-ons Manager.

Never use eval()! eval() is a dangerous function, which executes the code it's passed with the privileges of the caller.

The popup is specified as an HTML file, which can include CSS and JavaScript files, as a normal web page does.

Popups resize automatically to fit their content.