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- Theory
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Strict equality operator
We found all of the news stories on the page and added highlighting to them. This will help us to debug the code and configure filtering. We will filter news stories by category. The category of each news story is specified in its data attribute:
<article class="news-block" data-category="games">
…
</article>There are four possible values for the data-category: 'games', 'IT', 'HR', and 'cats'. The filter has the same values. When the user selects the category, we must compare the attribute value assigned to the news story with the selected value of the filter.
We already know how to compare two numbers and find out which one is larger. But how do you know that two values are equal to each other? We use the strict equality operator. It is indicated by three equal signs:
'a' === 'a'; // Result: true
'a' === 'b'; // Result: falseThe strict equality operator compares two values and returns true if they are equal and false if they are not equal. The values that the operator checks for are called operands.
We will use the strict equality operator to create filtering for the news site. Add a conditional statement inside the loop and compare the value of the data-category attribute for each news item with one of the possible filter values. As a result, highlighting will be added to news stories from only one category.
JavaScript also has a non-strict equality operator: ==. We will talk about it in one of the following chapters.
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<h1 class="visually-hidden">FlashNews news portal!</h1>
<div class="news-view">
<button class="row-view view-checked" type="button">Results list</button>
<button class="tile-view" type="button">Tile</button>
<select class="filter" name="news-filter">
<option value="IT">IT</option>
<option value="cats">Kitties</option>
<option value="games">Games</option>
<option value="HR">HR</option>
<option value="all" selected>All News</option>
</select>
</div>
<section class="news-list">
<h2 class="visually-hidden">All News</h2>
<article class="news-block" data-category="cats">
<img src="img/news-cat.jpg" alt="Cat eyes">
<div class="news-block-text">
<h3>Unique video!</h3>
<p>Discover the World Through the Eyes of Cats! Your life will never be the same…</p>
<span class="news-tag">#Kitties</span>
<time datetime="2020-03-24">March 24, 2020</time>
</div>
</article>
<article class="news-block" data-category="IT">
<img src="img/drone.jpg" alt="A small drone">
<div class="news-block-text">
<h3>Dronovirus</h3>
<p>The designers at the DogDrones.inc laboratory have assured that their drones cannot be carriers of dangerous
viruses…</p>
<span class="news-tag">#IT</span>
<time datetime="2019-12-22">December 22, 2019</time>
</div>
</article>
<article class="news-block" data-category="HR">
<img src="img/walk.jpg" alt="People go for walks">
<div class="news-block-text">
<h3>It can be healthy to go for a walk</h3>
<p>But it might not be if you take a stroll with the wrong people…</p>
<span class="news-tag">#HR</span>
<time datetime="2020-03-19">February 19, 2020</time>
</div>
</article>
<article class="news-block" data-category="games">
<img src="img/ar.jpg" alt="Person wearing virtual reality glasses">
<div class="news-block-text">
<h3>Augment your reality</h3>
<p>The editors of Flashnews! have prepared a gift for their subscribers…</p>
<span class="news-tag">#Games</span>
<time datetime="2020-02-18">February 18, 2020</time>
</div>
</article>
<article class="news-block" data-category="IT">
<img src="img/new-loop.jpg" alt="Infinite loops">
<div class="news-block-text">
<h3>Infinite loops: It’s time to end them</h3>
<p>British scientists have discovered that the ability of software to function directly depends on the presence of infinite loops in it.</p>
<span class="news-tag">#IT</span>
<time datetime="2019-10-16">October 16, 2019</time>
</div>
</article>
<article class="news-block" data-category="cats">
<img src="img/news-robot2.jpg" alt="A robot vacationing at a resort">
<div class="news-block-text">
<h3>What shocking news! It’s so scandalous! Such a sensation!</h3>
<p>It turns out that you don’t have to be a cat to start programming in JavaScript!</p>
<span class="news-tag">#Kitties</span>
<time datetime="2019-12-22">December 22, 2019</time>
</div>
</article>
<article class="news-block" data-category="HR">
<img src="img/new-research.jpg" alt="A man looks at a board with cards">
<div class="news-block-text">
<h3>From the world of psychology</h3>
<p>Studies show that if you do more, you can actually get more done.</p>
<span class="news-tag">#HR</span>
<time datetime="2019-10-12">October 12, 2019</time>
</div>
</article>
<article class="news-block" data-category="games">
<img src="img/new-drone.jpg" alt="Quadcopter">
<div class="news-block-text">
<h3>A quadcopter is not just a fancy toy</h3>
<p>Controlling the quadcopter allows you to develop agility, spatial thinking, and the ability to climb trees…
</p>
<span class="news-tag">#Games</span>
<time datetime="2019-11-21">November 21, 2019</time>
</div>
</article>
<article class="news-block" data-category="IT">
<img src="img/new-graph.jpg" alt="New library">
<div class="news-block-text">
<h3>New graphics library</h3>
<p>Now you can create a dashboard in just a matter of seconds.</p>
<span class="news-tag">#IT</span>
<time datetime="2019-10-14">October 14, 2019</time>
</div>
</article>
<article class="news-block" data-category="cats">
<img src="img/new-cat.jpg" alt="Cat at a laptop">
<div class="news-block-text">
<h3>This just in: SHOCKING NEWS! Secret photos from the cat nursery</h3>
<p>No one expected that THIS was going on behind the closed doors…</p>
<span class="news-tag">#Kitties</span>
<time datetime="2019-10-13">October 13, 2019</time>
</div>
</article>
</section>
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html {
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color: #9484f2;
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border-color: #9484f2;
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.dark-theme .subscription-link::before {
background-image: url("img/letter-dark.svg");
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position: fixed;
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bottom: 75px;
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color: #9484f2;
background-color: rgba(10, 9, 16, 0.6);
border-color: #9484f2;
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color: #6653d9;
background-color: rgba(10, 9, 16, 0.6);
border-color: #6653d9;
}
.shown {
display: inline-block;
}
/* Filter styles */
.filter {
display: flex;
padding: 7px 22px 7px 12px;
box-sizing: border-box;
margin: 0 0 0 auto;
font-size: inherit;
border: none;
border-radius: 2px;
-moz-appearance: none;
-webkit-appearance: none;
appearance: none;
background-repeat: no-repeat, repeat;
background-position: right 8px top 50%;
background-size: 8px auto;
}
.filter::-ms-expand {
display: none;
}
.filter:focus {
outline-offset: 0;
}
.light-theme .filter {
color: #ffffff;
background-color: #6653d9;
background-image: url("data:image/svg+xml;charset=US-ASCII,%3Csvg%20xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F2000%2Fsvg%22%20width%3D%22292.4%22%20height%3D%22292.4%22%3E%3Cpath%20fill%3D%22%23ffffff%22%20d%3D%22M287%2069.4a17.6%2017.6%200%200%200-13-5.4H18.4c-5%200-9.3%201.8-12.9%205.4A17.6%2017.6%200%200%200%200%2082.2c0%205%201.8%209.3%205.4%2012.9l128%20127.9c3.6%203.6%207.8%205.4%2012.8%205.4s9.2-1.8%2012.8-5.4L287%2095c3.5-3.5%205.4-7.8%205.4-12.8%200-5-1.9-9.2-5.5-12.8z%22%2F%3E%3C%2Fsvg%3E");
}
.light-theme .filter:hover {
background-color: #473c8d;
}
.light-theme .filter:focus {
outline-color: #b6aaff;
}
.dark-theme .filter {
color: #17161a;
background-color: #9484f2;
background-image: url("data:image/svg+xml;charset=US-ASCII,%3Csvg%20xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F2000%2Fsvg%22%20width%3D%22292.4%22%20height%3D%22292.4%22%3E%3Cpath%20fill%3D%22%2317161a%22%20d%3D%22M287%2069.4a17.6%2017.6%200%200%200-13-5.4H18.4c-5%200-9.3%201.8-12.9%205.4A17.6%2017.6%200%200%200%200%2082.2c0%205%201.8%209.3%205.4%2012.9l128%20127.9c3.6%203.6%207.8%205.4%2012.8%205.4s9.2-1.8%2012.8-5.4L287%2095c3.5-3.5%205.4-7.8%205.4-12.8%200-5-1.9-9.2-5.5-12.8z%22%2F%3E%3C%2Fsvg%3E");
}
.dark-theme .filter:hover {
background-color: #6653d9;
}
.dark-theme .filter:focus {
outline-color: #6653d9;
}
/* News tags styles */
.news-tag {
padding: 4px 8px;
margin: 0 auto 0 0;
border-radius: 12px;
}
.list-tiles-view .news-tag {
margin-bottom: 4px;
}
.light-theme .news-tag {
color: #aaaaaa;
background-color: #f2f2f2;
}
.dark-theme .news-tag {
color: #888888;
background-color: #0a0910;
}
/* News block highlighting */
.news-block.highlight {
padding-top: 6px;
padding-right: 6px;
padding-bottom: 10px;
padding-left: 6px;
border: 6px solid;
}
.light-theme .news-block.highlight {
border-color: #ff9900;
}
.dark-theme .news-block.highlight {
border-color: #e58a00;
}
.list-tiles-view .highlight img {
width: calc(100% + 12px);
top: -6px;
left: -6px;
height: 140px;
}
let articles = document.querySelectorAll('.news-block');
for (let article of articles) {
// Add a conditional statement here
article.classList.add('highlight');
}
let rowViewButton = document.querySelector('.row-view');
let tileViewButton = document.querySelector('.tile-view');
let newsList = document.querySelector('.news-list');
rowViewButton.onclick = function () {
rowViewButton.classList.add('view-checked');
tileViewButton.classList.remove('view-checked');
newsList.classList.remove('list-tiles-view');
};
tileViewButton.onclick = function () {
rowViewButton.classList.remove('view-checked');
tileViewButton.classList.add('view-checked');
newsList.classList.add('list-tiles-view');
};
let page = document.querySelector('.page');
let themeButton = document.querySelector('.theme-button');
themeButton.onclick = function () {
page.classList.toggle('light-theme');
page.classList.toggle('dark-theme');
};
let upButton = document.querySelector('.up-button');
window.onscroll = function () {
if (window.pageYOffset > 200) {
upButton.classList.add('shown');
} else {
upButton.classList.remove('shown');
}
};
upButton.onclick = function () {
window.scrollTo(0, 0);
};
Thanks! We’ll fix everything at once!
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- Inside the loop on line 4, add a conditional statement. Specify
article.dataset.category === 'IT'as a condition. - Move the instruction
article.classList.add('highlight');inside the conditional statement.
Please note how only those news stories from the IT category remain highlighted. - On line 4, change
'IT'to'cats'.
Please note how news items from the “Kitties” category are now highlighted.
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