Obj/Array References Day 14 of 30.

2023-03-03 09:48:37 -08:00 · 2023-03-03 09:48:37 -08:00 · 87880aa939
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+<!DOCTYPE html>
+<html lang="en">
+<head>
+  <meta charset="UTF-8">
+  <title>JS Reference VS Copy</title>
+  <link rel="icon" href="https://fav.farm/🔥" />
+</head>
+<body>
+
+  <script>
+    // start with strings, numbers and booleans
+    let age = 100;
+    let age2 = age;
+    console.log(age, age2);
+    age = 200;
+    console.log(age, age2);
+
+    let name = 'cool';
+    let name2 = name;
+    console.log(name, name2);
+    name = 'zero';
+    console.log(name, name2)
+
+    // 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[3] = '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] = 'Sphinx'
+    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:
+    const captain = person;
+    captain.number = 99;
+
+    // how do we take a copy instead?
+    const cap2 = Object.assign({}, person, { number: 99 });
+    console.log(cap2);
+
+    // We will hopefully soon see the object ...spread
+    const cap3 = {...person};
+
+    // 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 worlddrknss = {
+      name: 'Charles',
+      age: 100,
+      social: {
+        twitter: '@WorldDrknss',
+        facebook: 'skynetinctech'
+      }
+    }
+    console.log(worlddrknss);
+
+    const dev = Object.assign({}, worlddrknss);
+    const dev2 = JSON.parse(JSON.stringify(worlddrknss));
+
+  </script>
+
+</body>
+</html>