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Suggestions for Level 3 (#5)
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‎js/level3.js

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// Level 3
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/*
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WooHoo, you got so far on your first day! Great! But we still have more things for you.
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First of all, go to index.html file and replace our script from level2.js to current
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file - level3.js.
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PS: if you want few js files to be used simply add more scripts with those files.
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Introduction
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============
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WooHoo, you got so far on your first day! Great!
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But we still have more things for you. First of all, open index.html, and
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replace our script from level2.js to our current file — level3.js.
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P.S. If you want to use multiple js files simultaneously, simply add more
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script tags.
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*/
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/*
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Here we will talk a bit more about HTML, CSS and how JS can interact with them.
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So HTML - stands for Hyper Text Markup Language. It is a structure of the elements
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on the page.
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HTML:
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As you noticed it is divided on elements that looks like that:
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<header></header>, <p></p> etc - it is tags, each element on the page has opening
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and closing tag (NOTE: some tags are self-closing like <img>). Whole html file is wrapped
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in tag <html>, which contains of <head> and <body> tags. In <head> we keep different
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meta information, title and link to css files. <body> contains our actual content.
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Tags has a set of names which you can find here http://htmldog.com/references/html/tags/
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Any tag also can have different attributes (<div class="settings"></div> - tag div
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has a attribute class, that has name = 'settings').
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CSS:
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Stands for Cascading Style Sheets. CSS describes how HTML elements are to be
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displayed on screen. As you can see in css file when we need to target any element
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we can simply refer to the tag itself (footer{color: white;}), or to any attribute (class
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via '.settings', id via '#logo' etc). The list of css properties is huge, you can check
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on it here https://www.w3.org/TR/CSS21/propidx.html but don't worry, you don't need to
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remember it all.
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PS: difference between id and class is that tag with specific 'id' should be unique on
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the page, but many tags can have same class within the same page. Use 'id' only if
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you really need it!!
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Lets talk a little more about HTML, CSS, and how we can interact with them
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in JavaScript.
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Hypertext Markup Language (HTML)
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--------------------------------
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As you noticed, HTML is divided on elements that looks like this:
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<header></header>
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<p></p>
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etc
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We call these "tags". Each element on the page has an opening and closing
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tag. (NOTE: some tags are self-closing like <img>).
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The outermost tag in every HTML file is <html>.
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Inside the <html> tag you will find a <head> and <body> tag.
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In <head> we keep meta information, the page title and links to css files.
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<body> contains our actual content.
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For a full list of HTML tags, you can refer to this listing:
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http://htmldog.com/references/html/tags/
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HTML tags may contain attributes:
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<div class="settings"></div>
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This div has an attribute named class, that has value: 'settings'.
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Cascading Style Sheets (CSS)
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----------------------------
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CSS describes how HTML elements look.
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CSS files are comprised of 'declaration blocks'. Each declaration block is
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composed of a selector and a set of visual style rules. A declaration looks
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like this:
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[selector] {
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style-name: value;
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style-name: value;
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style-name: value;
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}
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Selectors specify which elements the visual styles are applied to.
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The most basic selectors refer to elements by their tag-name. They look
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like this:
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body {
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background-color: white;
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}
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Selectors can also refer to elements by their class attribute like this:
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.settings {
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margin: 0;
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}
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or IDs, like this:
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#logo {
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text-align: center;
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}
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The list of css properties is huge, you can read more here, if you're
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interested:
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https://www.w3.org/TR/CSS21/propidx.html
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Don't worry, you don't need to remember all of this immediately!
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*/
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/*
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Phew, lot's of new things. But let's come back to javaScript and see how we can interact
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with html.
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Phew, lots of new things. Let's come back to javaScript and see how we can
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interact with HTML.
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*/
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/*
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Accessing page objects.
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DOM - Stands for Document Object Model. It defines the logical structure of documents
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and the way a document is accessed and manipulated. So let's get things from the page
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and play around.
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To find and get nods(page elements) we can use querySelector one of the functions of
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JavaScript (in old browsers it might not work, in this case getElementById,
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getElementsByTagsName etc should be used).
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Let's get our twitter from the page.
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Accessing Elements
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==================
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Document Object Model (DOM)
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---------------------------
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The DOM is the javascript representation of the active HTML file. The DOM
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is available under a special global variable called 'document'. We can get
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specific nodes (page elements) with the DOM method: 'querySelector'.
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Let's get our twitter link from the page.
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Example:
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var ourTwitter = document.querySelector('.twitter');
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//we can store it in variable so we can use it after
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// we can store page elements in variables, just like any other value!
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*/
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//TODO: Now it's your turn - get the h1 tag from the page and store it into variable named
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//ourTitle. console.log it and see what you will get.
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// TODO: Now it's your turn — get the h1 tag from the page and store it into a
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// variable named ourTitle.
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// console.log it and see what you get!
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/*
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Getting a set of elements
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We also can get all elements with the same tag. So in the footer we have <ul>(unordered list)
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with 3 <li>(lists) inside. Let's get all of them
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Example:
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var mediaLinks = document.querySelectorAll('li'); //will get all <li> from the page
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Getting Similar Elements
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========================
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We also can get all elements with the same tag. In our footer, we have an
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unordered list (<ul>), with three list items (<li>) inside. Let's get all
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of them.
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Example:
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// will get all <li> from the page
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var mediaLinks = document.querySelectorAll('li');
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*/
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//TODO: get all <li> elements from the page in variable named mediaLinks
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// TODO: Get all <li> elements from the page in variable named mediaLinks.
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//TODO: now console.log mediaLinks.length
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// TODO: Now console.log mediaLinks.length
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//TODO: do you still remember arrays that we had in previous sections? Using this knowledge
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//iterate through whole meadiaLinks items and print them out.
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// TODO: Do you remember loops from level 2? Using this knowledge, iterate
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// through each mediaLinks item and console.log it.
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/*
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Ok, so far so good. But what if we need only content of our 'h1' tag? We have
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another property for it - .innerHTML
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Ok, so far so good. But what if we want only the text from our 'h1' tag?
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Page elements have another property for this: '.textContent'
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Example:
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ourTwitter.innerHTML;
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//we will get text '@NodeGirlsSydney'
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ourTwitter.textContent;
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// we will get text 'Twitter: @NodeGirlsSydney @NodeGirlsMelb'
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*/
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//TODO: get the content of 'h1' element and console.log it
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// TODO: get the content of 'h1' element and console.log it
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/*
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Change content
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we can change the content of the tags using the same .innerHTML property
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Editing Page Content
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====================
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We can change the content of the tags using the same .textContent property.
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Example:
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ourTwitter.innerHTML = '@ButenkoMe';
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console.log(ourTwitter.innerHTML);
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//guess what we will see on the page and in console?
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ourTwitter.textContent = '@ButenkoMe';
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console.log(ourTwitter.textContent);
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// guess what we will see on the page and in console?
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*/
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//TODO: change content of the 'h1' with anything you like
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// TODO: Make up a new title! Change the content of our 'h1' to anything you
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// like.
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/*
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Changing properties.
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We also can change and set attributes to our elements.
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Example:
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var ourTwitter = document.querySelector('.twitter');
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ourTwitter.id = "surprise";
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Editing Attributes
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==================
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We can also change and set attributes on our elements.
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Example:
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var ourTwitter = document.querySelector('.twitter');
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ourTwitter.id = "surprise";
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*/
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//TODO: replace the value of 'src' attribute for our img tag with "img/kittens.jpeg"
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// TODO: Update the value of the 'src' attribute of our img tag to
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// "img/kittens.jpeg"
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/*
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Accessing and changing styles
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So, let's do some css changes. We can do it with help of '.style' property and
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giving the css property just like we do in css file, the only change here is is - if is css
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property name has '-' in the name (like font-size etc) then dash will be deleted and
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next word starts with capital (fontSize) - this way of naming is called the CamelCase :)
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Editing Styles
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==============
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Let's change some styles. Page elements have a '.style' property. We can
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assign styles to the style property using the same names as in CSS files.
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(If a CSS property name has '-' in the name — like font-size — then the
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hyphen will be deleted and the next word starts with a capital instead —
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fontSize. This pattern of naming is called CamelCase.)
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Example:
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var ourTwitter = document.querySelector('.twitter');
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ourTwitter.style.backgroundColor = 'white';
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*/
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//TODO: get any element on the page and change some styles for it
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// TODO: get any element on the page and change some styles for it
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/*
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Creating new nodes (elements)
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Creating New Nodes (Elements)
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=============================
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The document object also provides ways to create nodes from scratch:
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document.createElement(tagName); --> create the element
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document.createTextNode(text); --> what text it should contain
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document.appendChild(); --> append it to the document
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document.appendChild(node); --> append it to the document
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Example:
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var pageNode = document.querySelector('body')[0];
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var newParagraph = document.createElement('p');
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var paragraphText = document.createTextNode('Squee!');
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*/
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//TODO: Well, do you still have kittens on your screen? I like both logo and kittens.
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//Let's create a new image with source logo and put it into header.
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//PS: you also can give styles to the new node that you create.
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// TODO: Well, do you still have kittens on your screen? I like both logo and
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// kittens. Let's create a new image that sources our original logo file, and
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// put it into header.
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//
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// P.S. You also can give styles to the new node that you create.
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////////////////////////////////////////////////////////////////////////
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//Congratulations! You have finished Part 3 of JavaScript Basics! //
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// Congratulations! You have finished Part 3 of JavaScript Basics! //
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// Stand up, stretch your legs, celebrate your achievement. //
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// I believe you deserve on some sweets today! //
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////////////////////////////////////////////////////////////////////////

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