Basic JavaScript 060

31-Use Bracket Notation to Find the First Character in a String

// Example
var firstLetterOfFirstName = "";
var firstName = "Ada";

firstLetterOfFirstName = firstName[0];

// Setup
var firstLetterOfLastName = "";
var lastName = "Lovelace";

// Only change code below this line
firstLetterOfLastName = lastName[0];

32-Use Bracket Notation to Find the NthtoLast Character in a String

// Example
var firstName = "Ada";
var thirdToLastLetterOfFirstName = firstName[firstName.length - 3];

// Setup
var lastName = "Lovelace";

// Only change code below this line
var secondToLastLetterOfLastName = lastName[lastName.length - 2];

33-Word Blanks

function wordBlanks(myNoun, myAdjective, myVerb, myAdverb) {
  var result = "";
  // Your code below this line
  result = myNoun + " " + myAdjective + " " + myVerb + " " + myAdverb;

  // Your code above this line
  return result;
}

// Change the words here to test your function
wordBlanks("dog", "big", "ran", "quickly");

34-Store Multiple Values in one Variable using JavaScript Arrays

// Example
var ourArray = ["John", 23];

// Only change code below this line.
var myArray = ["John", 25];

35-Nest one Array within Another Array

// Example
var ourArray = [["the universe", 42], ["everything", 101010]];

// Only change code below this line.
var myArray = [["John", "smart"],["Dudao", "stupid"]];

36-Access Array Data with Indexes

// Example
var ourArray = [1,2,3];
var ourData = ourArray[0]; // equals 1

// Setup
var myArray = [1,2,3];

// Only change code below this line.
var myData = myArray[0];

37-Modify Array Data With Indexes

// Example
var ourArray = [1,2,3];
ourArray[1] = 3; // ourArray now equals [1,3,3].

// Setup
var myArray = [1,2,3];

// Only change code below this line.

myArray[0] = 3;

38-Access MultiDimensional Arrays With Indexes

// Setup
var myArray = [[1,2,3], [4,5,6], [7,8,9], [[10,11,12], 13, 14]];

// Only change code below this line.
var myData = myArray[2][1];

39-Manipulate Arrays With push

// Example
var ourArray = ["Stimpson", "J", "cat"];
ourArray.push(["happy", "joy"]); 
// ourArray now equals ["Stimpson", "J", "cat", ["happy", "joy"]]

// Setup
var myArray = [["John", 23], ["cat", 2]];

// Only change code below this line.
myArray.push(["dog", 3]);

40-Manipulate Arrays With pop

// Example
var ourArray = [1,2,3];
var removedFromOurArray = ourArray.pop(); 
// removedFromOurArray now equals 3, and ourArray now equals [1,2]

// Setup
var myArray = [["John", 23], ["cat", 2]];

// Only change code below this line.
var removedFromMyArray = myArray.pop();

41-Manipulate Arrays With shift

// Example
var ourArray = ["Stimpson", "J", ["cat"]];
removedFromOurArray = ourArray.shift();
// removedFromOurArray now equals "Stimpson" and ourArray now equals ["J", ["cat"]].

// Setup
var myArray = [["John", 23], ["dog", 3]];

// Only change code below this line.
var removedFromMyArray = myArray.shift();

42-Manipulate Arrays With unshift

// Example
var ourArray = ["Stimpson", "J", "cat"];
ourArray.shift(); // ourArray now equals ["J", "cat"]
ourArray.unshift("Happy"); 
// ourArray now equals ["Happy", "J", "cat"]

// Setup
var myArray = [["John", 23], ["dog", 3]];
myArray.shift();

// Only change code below this line.
myArray.unshift(["Paul", 35]);

43-Shopping List

var myList = [];

myList = [ ["小米手環", 850], ["入門鋼筆", 39], ["便當", 50], ["皮包", 100], ["鋁箔包飲料", 10] ];

44-Write Reusable JavaScript with Functions

• 要 call、調用函數，要將括號 functonName()

• 大括號 curly braces

• 括號 parentheses

// Example
function ourReusableFunction() {
  console.log("Heyya, World");
}

ourReusableFunction();

// Only change code below this line
function reusableFunction() {
  console.log("Hi World");
}

reusableFunction();

45-Passing Values to Functions with Arguments

• Parameters 形式參數，在 () 中，像是佔位符

• arguments 實際參數，在 {} 中

• http://meebox.blogspot.tw/2012/07/parameter-argument.html

// Example
function ourFunctionWithArgs(a, b) {
  console.log(a - b);
}
ourFunctionWithArgs(10, 5); // Outputs 5

// Only change code below this line.
function functionWithArgs(num1, num2){
  console.log(num1 + num2);
}

functionWithArgs(1,2);
functionWithArgs(7,9);

46-Global Scope and Functions

• scope 作用域

• 沒用 var 宣告的變數，會自動變成全局 global 變數

// Declare your variable here
var myGlobal = 10;

function fun1() {
  // Assign 5 to oopsGlobal Here  
  oopsGlobal = 5;  
}

// Only change code above this line
function fun2() {
  var output = "";
  if (typeof myGlobal != "undefined") {
    output += "myGlobal: " + myGlobal;
  }
  if (typeof oopsGlobal != "undefined") {
    output += " oopsGlobal: " + oopsGlobal;
  }
  console.log(output);
}

47-Local Scope and Functions

• 這題的教學有點難懂 = =

function myLocalScope() {
  var myVar = 'use strict';


  console.log(myVar);
}
myLocalScope();

// Run and check the console
// myVar is not defined outside of myLocalScope

// Now remove the console log line to pass the test

48-Global vs Local Scope in Functions

• 優先權

// Setup
var outerWear = "T-Shirt";

function myOutfit() {
  // Only change code below this line
  var outerWear = "sweater";


  // Only change code above this line
  return outerWear;
}

myOutfit();

49-Return a Value from a Function with Return

// Example
function minusSeven(num) {
  return num - 7;
}

// Only change code below this line
function timesFive(num) {
  return num * 5;
}

50-Assignment with a Returned Value

• 將 function 返回的值 assign 變數

// Example
var changed = 0;

function change(num) {
  return (num + 5) / 3;
}

changed = change(10);

// Setup
var processed = 0;

function processArg(num) {
  return (num + 3) / 5;
}

// Only change code below this line
processed = processArg(7);

51-Stand in Line

• 不看 stack overflow 的話看不懂 orz

• 建立一個 function nextInLine(arr, item){} 函式，要產生以下的結果

  • nextInLine([], 1) should return 1

  • nextInLine([2], 1) should return 2

  • nextInLine([5,6,7,8,9], 1) should return 5

  • After nextInLine(testArr, 10), testArr[4] should be 10

• javascript - Writing a functions that removes an array and adds to the list - Stack Overflow

function nextInLine(arr, item) {
  // Your code here

  arr.push(item);
  var firstArrNum = arr.shift(); 
  return firstArrNum;  // Change this line
}

// Test Setup
var testArr = [1,2,3,4,5];

// Display Code
console.log("Before: " + JSON.stringify(testArr));
console.log(nextInLine(testArr, 6)); // Modify this line to test
console.log("After: " + JSON.stringify(testArr));

52-Understanding Boolean Values

function welcomeToBooleans() {

  // Only change code below this line.

  return true; // Change this line

  // Only change code above this line.
}

53-Use Conditional Logic with If Statements

// Example
function ourTrueOrFalse(isItTrue) {
  if (isItTrue) { 
    return "Yes, it's true";
  }
  return "No, it's false";
}

// Setup
function trueOrFalse(wasThatTrue) {

  // Only change code below this line.
    if(wasThatTrue){
      return "Yes, that was true";
    }
    return "No, that was false";


  // Only change code above this line.

}

// Change this value to test
trueOrFalse(true);

54-Comparison with the Equality Operator

// Setup
function testEqual(val) {
  if (val == 12) { // Change this line
    return "Equal";
  }
  return "Not Equal";
}

// Change this value to test
testEqual(10);

55-Comparison with the Strict Equality Operator

// Setup
function testStrict(val) {
  if (val === 7) { // Change this line
    return "Equal";
  }
  return "Not Equal";
}

// Change this value to test
testStrict(10);

56-Comparison with the Inequality Operator

// Setup
function testNotEqual(val) {
  if (val != 99) { // Change this line
    return "Not Equal";
  }
  return "Equal";
}

// Change this value to test
testNotEqual(10);

57-Comparison with the Strict Inequality Operator

// Setup
function testStrictNotEqual(val) {
  // Only Change Code Below this Line

  if (val !== 17) {

  // Only Change Code Above this Line

    return "Not Equal";
  }
  return "Equal";
}

// Change this value to test
testStrictNotEqual(10);

58-Comparison with the Greater Than Operator

• the Greater Than Operator 大於符號

function testGreaterThan(val) {
  if (val > 100) {  // Change this line
    return "Over 100";
  }

  if (val > 10 ) {  // Change this line
    return "Over 10";
  }

  return "10 or Under";
}

// Change this value to test
testGreaterThan(10);

59-Comparison with the Greater Than Or Equal To Operator

function testGreaterOrEqual(val) {
  if (val >= 20) {  // Change this line
    return "20 or Over";
  }

  if (val >= 10) {  // Change this line
    return "10 or Over";
  }

  return "9 or Under";
}

// Change this value to test
testGreaterOrEqual(10);

60-Comparison with the Less Than Operator

function testLessThan(val) {
  if (val <25 ) {  // Change this line
    return "Under 25";
  }

  if (val < 55 ) {  // Change this line
    return "Under 55";
  }

  return "55 or Over";
}

// Change this value to test
testLessThan(10);