设计开发
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HTML Uniform Resource Locators A URL is another word for a web address. A URL can be composed of words (e.g. w3schools.com), or an Internet Protocol (IP) address (e.g. 192.68.20.50). Most people enter the name when surfing, because names are easier to remember than numbers. URL - Uniform Resource Locator Web browsers request pages from web servers by using a URL. A Uniform Resource Locator (URL) is used to address a document (or other data) on the web. A web address like https://www.w3schools.com/html/default.asp follows these syntax rules: scheme://prefix.domain:port/path/filename Explanation: scheme - defines the type of Internet service (most common i…
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HTML Encoding (Character Sets) The HTML charset Attribute To display an HTML page correctly, a web browser must know which character set to use. The character set is specified in the <meta> tag: <meta charset="UTF-8"> The HTML specification encourages web developers to use the UTF-8 character set. UTF-8 covers almost all of the characters and symbols in the world! Learn More: Full UTF-8 Reference The ASCII Character Set ASCII was the first character encoding standard for the web. It defined 128 different latin characters that could be used on the internet: English letters (a-z and A-Z) Numbers (0-9) Some special characters: ! $ + - ( …
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Using Emojis in HTML What are Emojis? Emojis look like images, but they are not. Emojis are letters (characters) from the UTF-8 (Unicode) character set: 😄 😍 💗 UTF-8 covers almost all of the characters and symbols in the world. Emoji Value 🗻🗻🗼🗼🗽🗽🗾🗾🗿🗿😀😀😁😁😂😂😃😃😄😄😅😅 HTML Emojis Examples Smileys 😀 😂 😊 😎 😜 Hands ✌ ✊ ☝ ✋ 👌 People 👮 🧕 👦 💏 🤴 Office 📈 💻 📌 📆 📒 Places ⛺ 🌋 🗽 🗿 🏢 Transport 🚈 🚗 🚢 🚌 🚀 Animals 🐴 🐕 🐘 🐻 🐞 Food ☕ 🌭 🍞 🍩 🍣 Plants 🌴 🌳 🌼 🍁 🥑 Fruits 🍇 🍊 🍏 🥝 🥥 Sports ⚽ 🏆 🤿 🏋 ⛳ Ea…
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HTML Symbols HTML Symbol Entities Symbols or letters that are not present on your keyboard can be added to HTML using entities. To add such symbols to an HTML page, you can use the entity name or the entity number (a decimal or a hexadecimal reference) for the symbol: Example Display the euro sign: <p>I will display €</p> <p>I will display €</p> <p>I will display €</p> Will display as: I will display € I will display € I will display € Some HTML Symbol Entities Char Number Entity Description © © © COPYRIGHT ® ® ® REGISTERED TRADEMARK …
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HTML Entities Reserved characters in HTML must be replaced with entities: < (less than) = < > (greater than) = > HTML Character Entities Some characters are reserved in HTML. If you use the less than (<) or greater than (>) signs in your HTML text, the browser might mix them with tags. Entity names or entity numbers can be used to display reserved HTML characters. Entity names look like this: &entity_name; Entity numbers look like this: &#entity_number; To display a less than sign (<) we must write: < or < Entity names are easier to remember than entity numbers. Non-breaking Space A commonly u…
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HTML Style Guide Consistent, clean, and tidy HTML code makes it easier for others to read and understand your code. Here are some guidelines and tips for creating good HTML code. Always Declare Document Type Always declare the document type as the first line in your document. The correct document type for HTML is: <!DOCTYPE html> Use Lowercase Element Names HTML allows mixing uppercase and lowercase letters in element names. However, we recommend using lowercase element names, because: Mixing uppercase and lowercase names looks bad Developers normally use lowercase names Lowercase looks cleaner Lowercase is easier to type Good: <body&…
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HTML Semantic Elements Semantic elements = elements with a meaning. What are Semantic Elements? A semantic element clearly describes its meaning to both the browser and the developer. Examples of non-semantic elements: <div> and <span> - Tells nothing about its content. Examples of semantic elements: <img>, <table>, and <article> - Clearly defines its content. Semantic Elements in HTML Many web sites contain HTML code like: <div id="nav"> <div class="header"> <div id="footer"> to indicate navigation, header, and footer. In HTML there are several semantic elements that can be used to define different parts of a we…
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HTML Computer Code Elements HTML contains several elements for defining user input and computer code. Example <code> x = 5; y = 6; z = x + y; </code> HTML <kbd> For Keyboard Input The HTML <kbd> element is used to define keyboard input. The content inside is displayed in the browser's default monospace font. Example Define some text as keyboard input in a document: <p>Save the document by pressing <kbd>Ctrl + S</kbd></p> Result: Save the document by pressing Ctrl + S HTML <samp> For Program Output The HTML <samp> element is used to define sample output from a computer program. The c…
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HTML Responsive Web Design Responsive web design is about creating web pages that look good on all devices! A responsive web design will automatically adjust for different screen sizes and viewports. What is Responsive Web Design? Responsive Web Design is about using HTML and CSS to automatically resize, hide, shrink, or enlarge, a website, to make it look good on all devices (desktops, tablets, and phones): Try it Yourself » Setting The Viewport To create a responsive website, add the following <meta> tag to all your web pages: Example <meta name="viewport" content="width=device-width, initial-scale=1.0"> This will set the viewport of…
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HTML Layout Elements and Techniques Websites often display content in multiple columns (like a magazine or a newspaper). Example Cities London Paris Tokyo London London is the capital city of England. It is the most populous city in the United Kingdom, with a metropolitan area of over 13 million inhabitants. Standing on the River Thames, London has been a major settlement for two millennia, its history going back to its founding by the Romans, who named it Londinium. Footer HTML Layout Elements HTML has several semantic elements that define the different parts of a web page: <h…
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HTML - The Head Element The HTML <head> element is a container for the following elements: <title>, <style>, <meta>, <link>, <script>, and <base>. The HTML <head> Element The <head> element is a container for metadata (data about data) and is placed between the <html> tag and the <body> tag. HTML metadata is data about the HTML document. Metadata is not displayed on the page. Metadata typically define the document title, character set, styles, scripts, and other meta information. The HTML <title> Element The <title> element defines the title of the document. The title must be text…
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HTML File Paths A file path describes the location of a file in a web site's folder structure. File Path Examples PathDescription <img src="picture.jpg"> The "picture.jpg" file is located in the same folder as the current page <img src="images/picture.jpg"> The "picture.jpg" file is located in the images folder in the current folder <img src="/images/picture.jpg"> The "picture.jpg" file is located in the images folder at the root of the current web <img src="../picture.jpg"> The "picture.jpg" file is located in the folder one level up from the current folder HTML File Paths A file path describes the location of a file in a web site…
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HTML JavaScript JavaScript makes HTML pages more dynamic and interactive. Example My First JavaScript Click me to display Date and Time The HTML <script> Tag The HTML <script> tag is used to define a client-side script (JavaScript). The <script> element either contains script statements, or it points to an external script file through the src attribute. Common uses for JavaScript are image manipulation, form validation, and dynamic changes of content. To select an HTML element, JavaScript most often uses the document.getElementById() method. This JavaScript example writes "Hello JavaScript!" into an HTML element with id="demo": E…
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HTML Iframes An HTML iframe is used to display a web page within a web page. HTML Iframe Syntax The HTML <iframe> tag specifies an inline frame. An inline frame is used to embed another document within the current HTML document. Syntax <iframe src="url" title="description"></iframe> Tip: It is a good practice to always include a title attribute for the <iframe>. This is used by screen readers to read out what the content of the iframe is. Iframe - Set Height and Width Use the height and width attributes to specify the size of the iframe. The height and width are specified in pixels by default: Example <iframe src="demo…
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HTML Buttons Buttons let users interact with a web page. They can submit forms, run JavaScript, or trigger different actions when clicked. HTML Button The HTML <button> element defines a clickable button. By itself, the button does nothing until you add an action to it. Example <button>Click Me</button> Styling HTML Buttons Buttons are often styled with CSS: Example <button class="mytestbtn">Green Button</button> Disabled Buttons Use the disabled attribute to make a button unclickable: Example <button disabled>Disabled Button</button> Tip: Disabled buttons cannot be clicked and usually a…
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HTML id Attribute The HTML id attribute is used to specify a unique id for an HTML element. You cannot have more than one element with the same id in an HTML document. The id Attribute The id attribute specifies a unique id for an HTML element. The value of the id attribute must be unique within the HTML document. The id attribute is used to point to a specific style declaration in a style sheet. It is also used by JavaScript to access and manipulate the element with the specific id. The syntax for id is: write a hash character (#), followed by an id name. Then, define the CSS properties within curly braces {}. In the following example we have an <h1>…
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HTML class Attribute The HTML class attribute is used to specify a class for an HTML element. Multiple HTML elements can share the same class. The class Attribute The class attribute is often used to point to a class name in a style sheet. It can also be used by JavaScript to access and manipulate elements with the specific class name. In the following example we have three <div> elements with a class attribute with the value of "city". All of the three <div> elements will be styled equally according to the .city style definition in the head section: Example <!DOCTYPE html> <html> <head> <style> .city { backgroun…
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HTML Div Element The <div> element is used as a container for other HTML elements. The <div> Element The <div> element is by default a block element, meaning that it takes all available width, and comes with line breaks before and after. Example A <div> element takes up all available width: Lorem Ipsum <div>I am a div</div> dolor sit amet. Result Lorem Ipsum I am a div dolor sit amet. The <div> element has no required attributes, but style, class and id are common. <div> as a container The <div> element is often used to group sections of a web page together. Example A <div>…
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HTML Block and Inline Elements Every HTML element has a default display value, depending on what type of element it is. The two most common display values are block and inline. Block-level Elements A block-level element always starts on a new line, and the browsers automatically add some space (a margin) before and after the element. A block-level element always takes up the full width available (stretches out to the left and right as far as it can). Two commonly used block elements are: <p> and <div>. The <p> element defines a paragraph in an HTML document. The <div> element defines a division or a section in an HTML document. Th…
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HTML Lists HTML lists allow web developers to group a set of related items in lists. Example An unordered HTML list: Item Item Item Item An ordered HTML list: First item Second item Third item Fourth item Unordered HTML List An unordered list starts with the <ul> tag. Each list item starts with the <li> tag. The list items will be marked with bullets (small black circles) by default: Example <ul> <li>Coffee</li> <li>Tea</li> <li>Milk</li> </ul> Ordered HTML List An ordered list starts with the <ol> tag. Each list item starts with the <li&…
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HTML Tables HTML tables allow web developers to arrange data into rows and columns. Example Company Contact Country Alfreds Futterkiste Maria Anders Germany Centro comercial Moctezuma Francisco Chang Mexico Ernst Handel Roland Mendel Austria Island Trading Helen Bennett UK Laughing Bacchus Winecellars Yoshi Tannamuri Canada Magazzini Alimentari Riuniti Giovanni Rovelli Italy Define an HTML Table A table in HTML consists of table cells inside rows and columns. Example A simple HTML table: <table> <tr> <th…
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HTML Page Title Every web page should have a page title to describe the meaning of the page. The Title Element The <title> element adds a title to your page: Example <!DOCTYPE html> <html> <head> <title>HTML Tutorial</title> </head> <body> The content of the document...... </body> </html> The title is shown in the browser's title bar: What is a Good Title? The title should describe the content and the meaning of the page. The page title is very important for search engine optimization (SEO). The text is used by search engine algorithms to decide the order when listing pages i…
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HTML Favicon A favicon is a small image displayed next to the page title in the browser tab. How To Add a Favicon in HTML You can use any image you like as your favicon. You can also create your own favicon on sites like https://www.favicon.cc. Tip: A favicon is a small image, so it should be a simple image with high contrast. A favicon image is displayed to the left of the page title in the browser tab, like this: To add a favicon to your website, either save your favicon image to the root directory of your webserver, or create a folder in the root directory called images, and save your favicon image in this folder. A common name for a favicon image is …
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HTML Images Images can improve the design and the appearance of a web page. Example <img src="pic_trulli.jpg" alt="Italian Trulli"> Example <img src="img_girl.jpg" alt="Girl in a jacket"> Example <img src="img_chania.jpg" alt="Flowers in Chania"> HTML Images Syntax The HTML <img> tag is used to embed an image in a web page. Images are not technically inserted into a web page; images are linked to web pages. The <img> tag creates a holding space for the referenced image. The <img> tag is empty, it contains attributes only, and does not have a closing tag. The <img> tag has …
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HTML Links Links are found in nearly all web pages. Links allow users to click their way from page to page. HTML Links - Hyperlinks HTML links are hyperlinks. You can click on a link and jump to another document. When you move the mouse over a link, the mouse arrow will turn into a little hand. Note: A link does not have to be text. A link can be an image or any other HTML element! HTML Links - Syntax The HTML <a> tag defines a hyperlink. It has the following syntax: <a href="url">link text</a> The most important attribute of the <a> element is the href attribute, which indicates the link's destination. The link text is…
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