workshop notes

week-3/workshop.js

@@ -0,0 +1,250 @@
+/*
+scope, place you can access variable within code base
+
+function foo() {
+    let y = 2;
+    return y;
+}
+
+let z = foo();
+
+console.log(z);
+cannot log y as not exist within scope!
+
+var old JS (should not be used)
+
+scope, global (outside of everything, top of page not indented)
+scope, block = only used within that block i.e. "scoped"
+
+block = code within { }
+
+function foo() {block}
+if() {block}
+while() {block}
+
+any loop etc..
+
+let name = "jack" < global
+if() {
+    name = "tom" it is reassigned and takes the new global spot
+}
+
+if() {
+    let name = "bob" makes a new variable called name within scope
+}
+
+let name;
+
+^ vairable set as undefined
+
+if() {
+    name = "test"
+}
+
+sets the value later
+
+
+function grandfather() {
+    let name = "hammad";
+    // likes is not accessible here
+    function parent() {
+        //name is accessible here
+        //likes is not
+        function childe () {
+            // inner levle of scope
+            // name available
+            let likes = "code"
+
+            console.log(name, likes)
+        }
+        child();
+    }
+    parent();
+}
+grandfather();
+
+can use parent scope if nested but not child!!!
+
+vairable shadowing, variable in nested scope, same name as variable higher up
+one closest to you wins, if in current scope that is used!
+
+not override
+
+can reassign variable in a nested function/if
+
+let x = 10;
+
+function 222() {
+    let name = "dan"
+
+    if(x > 5) {
+        name = "jack";
+    }
+}
+
+^ this will work,
+
+var = function scope or global,
+
+function scope = if a variable is included within a function it is only 
+available in that function
+
+function{
+    if {
+        var x
+    }
+    console.log(x) works!
+}
+
+if var used within if statement it is global as not function scoped!!!
+
+if two var used with same name within if statements so global? they do not clash!
+also 2nd overrides first
+
+var hoists variables up!
+
+let / const = work identically with scope
+
+
+Jacks JS rules,
+
+1. do not use Var... ever!
+2. if changing value over time use let 
+3. if wont ever change value use const
+
+2/3 helps reader understand
+
+if const. cant use = "something else"!
+
+if const name = "jack" know it wont change
+let faveColour = "red" know that it can change
+
+can rule out of debugging as variable does not change
+
+const names = ["jack"]
+cannot do 
+names = ["alice", "Jack"]
+
+can do
+names.push("alice")
+
+const array means names must reference the array, array can be updated but
+variable cannot be re assigned
+
+eslint to update var that do not change to const!
+
+cannot do const name = x
+let name = y
+
+on vs code use [-] next to functions to see scope!
+
+if no let/var/const will be used as a global variable
+
+d = 1
+
+^ global
+
+
+~~~~~~~~~~~
+
+arrays and destructuring
+
+let fruits = ["apple", "orange"]
+
+let firstFruit = fruits[0]
+
+console.log(firstFruit)
+
+
+
+
+let familyMembers = ["Homer", "Marge", "Bart", "Lisa", "Maggie"];
+// Create variables to store the values here
+
+let dad = familyMembers[0];
+let mom = familyMembers[1];
+let son = familyMembers[2];
+let daughter = familyMembers[3];
+let baby = familyMembers[4];
+
+console.log(
+  `In the Simpsons family, ${dad} and ${mum} are the parents. ${son} is the son, ${daughter} is the daughter, and ${baby} is the baby.`
+);
+
+destructure extract values from array in 1 line of code,
+
+let animals = ["cat", "dog"]
+
+let [CAT, DOG] = animals;
+
+console.log(`we have a ${cat} and 2  )
+
+...rest ^rest of the values in the array
+
+then [rest] or [rest[0], rest[1]]
+*/
+
+// let sentence = ["Hello", "Code", "Your", "Future"];
+
+// // let firstWord = item[0];
+// // let secondWord = item[1];
+// // let thirdWord = item[2];
+// // let fourthWord = item[3];
+
+// let [firstWord, secondWord, thirdWord, fourthWord] = sentence;
+
+// console.log(
+//   `FirstWord: ${firstWord}, SecondWord: ${secondWord}, ThirdWord: ${thirdWord}, FourthWord: ${fourthWord},`
+// );
+// let animals = [{name: "cat", age: 4},{name: "dog", age: 6}]
+// let [cat, dog] = animals
+// console.log(dog.name, cat.name)
+
+// let citiesByPopulation = [
+//   { name: "London", population: 8000000 },
+//   { name: "Birmingham", population: 1000000 },
+//   { name: "Glasgow", population: 600000 },
+//   { name: "Manchester", population: 500000 },
+// ];
+// // Assign variables using array destructuring on this line
+
+// let [london, birmingham, glasgow, manchester] = citiesByPopulation;
+
+// console.log(`${london.name} population is ${london.population}`);
+// console.log(`${birmingham.name} population is ${birmingham.population}`);
+// console.log(`${glasgow.name} population is ${glasgow.population}`);
+// console.log(`${manchester.name} population is ${manchester.population}`);
+
+//rest[0].name works!
+
+/*
+destructure object 
+
+let claire = {
+    name: "Claire",
+    age: 21,
+    occupation: "manager"
+}
+
+let {name, age, occupation} = claire
+
+console.log(claire)
+
+function numbers(a,b) {
+    return [a,b]
+}
+console.log(numbers(2,5))
+
+let [num1, num2] = numbers(2, 5);
+*/
+
+// function sumAndMultiply(a, b) {
+//   return [a + b, a * b];
+// }
+// // Assign variables using array destructuring on this line
+
+// let [sum, multiply] = sumAndMultiply(2, 5);
+
+// console.log(
+//   `The sum of the two numbers is ${sum}, the multiplication of the two numbers is ${multiply}`
+// );