text
The opening <html> tag indicates that anything between it and a closing </html> tag is HTML code.
The <body> tag indicates that anything between it and the closing
</body> tag should be shown inside the main browser window.
Words between <h1> and </h1> are a main heading.
A paragraph of text appears between these <p> and </p> tags.
Words between <h2> and </h2> form a sub-heading.
Here is another paragraph between opening <p> and closing </p> tags
the loops
Conditional statements allow your code to make
decisions about what to do next.
Comparison operators (===, ! ==, ==, ! =, <, >, <=, =>)
are used to compare two operands.
Logical operators allow you to combine more than one
set of comparison operators.
if … else statements allow you to run one set of code
if a condition is true, and another if it is false.
switch statements allow you to compare a value
against possible outcomes (and also provides a default
option if none match).
Data types can be coerced from one type to another.
All values evaluate to either truthy or falsy.
There are three types of loop: for, while, and
do … while. Each repeats a set of statements.
document object
The browser represents the page using a DOM tree.
DOM trees have four types of nodes: document nodes,
element nodes, attribute nodes, and text nodes.
You can select element nodes by their id or cl ass
attributes, by tag name, or using CSS selector syntax.
Whenever a DOM query can return more than one
node, it will always return a Nadel i st.
From an element node, you can access and update its
content using properties such as textContent and
i nnerHTML or using DOM manipulation techniques.
An element node can contain multiple text nodes and
child elements that are siblings of each other.
In older browsers, implementation of the DOM is
inconsistent (and is a popular reason for using jQuery).
cBrowsers offer tools for viewing the DOM tree .
instruction
A script is made up of a series of statements. Each
statement is like a step in a recipe.
Scripts contain very precise instructions. For example,
you might specify that a value must be remembered
before creating a calculation using that value.
Variables are used to temporarily store pieces of
information used in the script.
Arrays are special types of variables that store more
than one piece of related information.
JavaScript distinguishes between numbers (0-9),
strings (text), and Boolean values (true or false).
Expressions evaluate into a single value.
Expressions rely on operators to calculate a value.
CSS
treats each HTML e XX lement as if it appears inside
its own box and uses rules to indicate how that
element should look.
Rules are made up of selectors (that specify the
elements the rule applies to) and declarations (that
indicate what these elements should look like).
Different types of selectors allow you to target your
rules at different elements.
Declarations are made up of two parts: the properties
of the element that you want to change, and the values
of those properties. For example, the font-family
property sets the choice of font, and the value arial
specifies Arial as the preferred typeface.
CSS rules usually appear in a separate document,
although they may appear within an HTML page.
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