Day14_30DayJS Array and Object reference vs copy

archeana · Jan 21, 2024 · dbae6e0 · dbae6e0
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diff --git a/Day_14/index.html b/Day_14/index.html
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+<!DOCTYPE html>
+<html lang="en">
+
+<head>
+    <meta charset="UTF-8">
+    <title>JS Reference VS Copy</title>
+    <link rel="stylesheet" href="style.css">
+</head>
+
+<body>
+    <div class="navigation">
+        <a class="card previous-card" href="https://archeana.github.io/JS30/Day_13/index.html"
+            onclick="goToPreviousProject()">
+            <span>Previous</span>
+        </a>
+        <a class="card home-card" href="https://archeana.github.io/JS30/" onclick="goToHomepage()">
+            <span>Home</span>
+        </a>
+        <a class="card next-card" href="#" onclick="goToNextProject()">
+            <span>Next</span>
+        </a>
+    </div>
+    <br>
+    <p><em>Psst: have a look at the JavaScript Console or just skip to the next project</em> 💁</p>
+    <script>
+        // start with strings, numbers and booleans
+        // let age = 100;
+        // let age2 = age;
+        // console.log(age, age2);
+        // age = 200;
+        // console.log(age, age2);
+        // Let's say we have an array
+        const players = ['Wes', 'Sarah', 'Ryan', 'Poppy'];
+
+
+        // and we want to make a copy of it.
+        const team = players;
+
+        console.log(players, team);
+
+        // You might think we can just do something like this:
+        // team[5] = 'Lux';
+        // however what happens when we update that array?
+
+        // now here is the problem!
+
+        // oh no - we have edited the original array too!
+
+        // Why? It's because that is an array reference, not an array copy. They both point to the same array!
+
+        // So, how do we fix this? We take a copy instead!
+        const team2 = players.slice();
+        // one way
+
+        // or create a new array and concat the old one in
+        const team3 = [].concat(players);
+
+        // or use the new ES6 Spread
+        const team4 = [...players];
+        team4[3] = 'heeee hawww';
+        console.log(team4);
+
+        const team5 = Array.from(players);
+        // now when we update it, the original one isn't changed
+
+        // The same thing goes for objects, let's say we have a person object
+
+        // with Objects
+        const person = {
+            name: 'Wes Bos',
+            age: 80
+        };
+
+        // and think we make a copy:
+
+        // how do we take a copy instead?
+        const cap2 = Object.assign({}, person, { number: 99, age: 12 });
+        console.log(cap2);
+
+        // We will hopefully soon see the object ...spread
+
+        // Things to note - this is only 1 level deep - both for Arrays and Objects. lodash has a cloneDeep method, but you should think twice before using it.
+
+        const wes = {
+            name: 'Wes',
+            age: 100,
+            social: {
+                twitter: '@wesbos',
+                facebook: 'wesbos.developer'
+            }
+        };
+
+        console.clear();
+        console.log(wes);
+        // this is how we copy- assign uses one level and not all of them
+        const dev = Object.assign({}, wes);
+        // this how you can clone (he does not recomend)
+        const dev2 = JSON.parse(JSON.stringify(wes));
+
+    </script>
+
+</body>
+
+</html>
diff --git a/Day_14/style.css b/Day_14/style.css
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+html {
+    box-sizing: border-box;
+  }
+
+  *, *:before, *:after {
+    box-sizing: inherit;
+  }
+
+
+
+
+  body {
+    text-align: center;
+    background: #193549;
+    color: white;
+    font-family: 'helvetica neue', sans-serif;
+    font-weight: 100;
+    font-size: 1.4em;
+    position: relative;
+}
+
+
+
+.navigation {
+    color: white;
+    font-family: 'helvetica neue', sans-serif;
+    position: fixed;
+    top: 20px;
+    left: 50%;
+    transform: translateX(-50%);
+    display: flex;
+    align-items: center;
+    justify-content: center;
+    z-index: 1000;
+}
+
+.card-back{
+    left: auto;
+}
+
+.card {
+    width: 100px;
+    height: 50px;
+    margin: 5px;
+    font-size: 20px;
+    background-color: #A2748B;
+    color: #ffffff;
+    border: none;
+    border-radius: 5px;
+    cursor: pointer;
+    overflow: hidden;
+    transition: 1s ease;
+    text-align: center;
+    align-items: center;
+    justify-content: space-between;
+    line-height: 16px;
+    display: flex;
+    justify-content: center;
+    position: relative;
+}