> For the complete documentation index, see [llms.txt](https://ayugioh2003.gitbook.io/free-code-camp-practice/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://ayugioh2003.gitbook.io/free-code-camp-practice/front-end-development-certification/basic-javascript/basic-javascript-90.md).

# Basic JavaScript 090

61-Comparison with the Less Than Or Equal To Operator

```javascript
function testLessOrEqual(val) {
  if (val <= 12) {  // Change this line
    return "Smaller Than or Equal to 12";
  }

  if (val <= 24) {  // Change this line
    return "Smaller Than or Equal to 24";
  }

  return "25 or More";
}

// Change this value to test
testLessOrEqual(10);
```

62-Comparisons with the Logical And Operator

```javascript
function testLogicalAnd(val) {
  // Only change code below this line

  if ( val<=50 && val>= 25 ) {
    return "Yes";
  }

  // Only change code above this line
  return "No";
}

// Change this value to test
testLogicalAnd(10);
```

63-Comparisons with the Logical Or Operator

```javascript
function testLogicalOr(val) {
  // Only change code below this line

  if (val<10 || val>20) {
    return "Outside";
  }

  // Only change code above this line
  return "Inside";
}

// Change this value to test
testLogicalOr(15);
```

64-Introducing Else Statements

```javascript
function testElse(val) {
  var result = "";
  // Only change code below this line

  if (val > 5) {
    result = "Bigger than 5";
  } else {
    result = "5 or Smaller";
  }

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

// Change this value to test
testElse(4);
```

65-Introducing Else If Statements

```javascript
function testElseIf(val) {
  if (val > 10) {
    return "Greater than 10";
  } 

  else if(val < 5) {
    return "Smaller than 5";
  } 

  else{
    return "Between 5 and 10";  
  }

}

// Change this value to test
testElseIf(7);
```

66-Logical Order in If Else Statements

```javascript
function orderMyLogic(val) {
  if (val < 5) {
    return "Less than 5";
  } else if (val < 10) {
    return "Less than 10";
  } else {
    return "Greater than or equal to 10";
  }
}

// Change this value to test
orderMyLogic(7);
```

67-Chaining If Else Statements

```javascript
function testSize(num) {
  // Only change code below this line

  var result = "";

  if (num>=20){
    result = "Huge";
  }

  else if (num<5){
    result = "Tiny";
  }   

  else if (num<10){
    result = "Small";
  }  

  else if (num<15){
    result = "Medium";
  }

  else if (num<20){
    result = "Large";
  }

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

// Change this value to test
testSize(19);
```

68-Golf Code

```javascript
function golfScore(par, strokes) {
  // Only change code below this line

  var result = "";

  if (strokes==1){
    result = "Hole-in-one!";
  }

  else if (strokes<=par-2){
    result = "Eagle";
  }

  else if (strokes==par-1){
    result = "Birdie";
  }

  else if (strokes===par){
    result = "Par";
  }

  else if (strokes==par+1){
    result = "Bogey";
  }

  else if (strokes==par+2){
    result = "Double Bogey";
  }

  else if (strokes>=par+3){
    result = "Go Home!";
  }


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

// Change these values to test
golfScore(5, 4);
```

69-Selecting from many options with Switch Statements

```javascript
function caseInSwitch(val) {
  var answer = "";
  // Only change code below this line

  switch (val){
    case 1:
      answer = "alpha";
      break;

    case 2:
      answer = "beta";
      break;

    case 3:
      answer = "gamma";
      break;

    case 4:
      answer = "delta";
      break;

  }


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

// Change this value to test
caseInSwitch(1);
```

70-Adding a default option in Switch statements

```javascript
function switchOfStuff(val) {
  var answer = "";
  // Only change code below this line

  switch(val){
    case "a":
      answer = "apple";
      break;

    case "b":
      answer = "bird";
      break;

    case "c":
      answer = "cat";
      break;

    default:
      answer = "stuff";
  }

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

// Change this value to test
switchOfStuff("a");
```

71-Multiple Identical Options in Switch Statements

```javascript
function sequentialSizes(val) {
  var answer = "";
  // Only change code below this line

  switch(val){
    case 1:
    case 2:
    case 3:
      answer = "Low";
      break;

    case 4:
    case 5:
    case 6:
      answer = "Mid";
      break;

    case 7:
    case 8:
    case 9:
      answer = "High";
      break;
  }

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

// Change this value to test
sequentialSizes(1);
```

72-Replacing If Else Chains with Switch

```javascript
function chainToSwitch(val) {
  var answer = "";
  // Only change code below this line

  switch(val){
    case "bob":
      answer = "Marley";
      break;

    case 42:
      answer = "The Answer";
      break;

    case 1:
      answer = "There is no #1";
      break;

    case 99:
      answer = "Missed me by this much!";
      break;

    case 7:
      answer = "Ate Nine";
      break;
  }

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

// Change this value to test
chainToSwitch(7);
```

73-Returning Boolean Values from Functions

```javascript
function isLess(a, b) {
  // Fix this code
  return a < b;
}

// Change these values to test
isLess(10, 15);
```

74-Return Early Pattern for Functions

```javascript
// Setup
function abTest(a, b) {
  // Only change code below this line

  if (a<0 || b<0){
    return undefined;
  }

  // Only change code above this line

  return Math.round(Math.pow(Math.sqrt(a) + Math.sqrt(b), 2));
}

// Change values below to test your code
abTest(2,2);
```

75-Counting Cards

```javascript
var count = 0;

function cc(card) {
  // Only change code below this line

  switch(card){
    case 2:
    case 3:
    case 4:
    case 5:
    case 6:
      count = count + 1;
      break;
    case 7:
    case 8:
    case 9:
      break;
    case 10:
    case "J":
    case "Q":
    case "K":
    case "A":
      count = count -1;
      break;
  }

  if(count===0){
    return "0 Hold";
  } 
  else if(count>0){
    return count + " Bet";
  }
  else if(count<0){
    return count + " Hold";
  }

  // Only change code above this line
}

// Add/remove calls to test your function.
// Note: Only the last will display
cc(2); cc(3); cc(7); cc('K'); cc('A');
```

76-Build JavaScript Objects

```javascript
// Example
var ourDog = {
  "name": "Camper",
  "legs": 4,
  "tails": 1,
  "friends": ["everything!"]
};

// Only change code below this line.

var myDog = {
  "name": "snoopy",
  "legs": 2,
  "tails": 1,
  "friends": ["lala", "xixi"]
};
```

77-Accessing Objects Properties with the Dot Operator

```javascript
// Setup
var testObj = {
  "hat": "ballcap",
  "shirt": "jersey",
  "shoes": "cleats"
};

// Only change code below this line

var hatValue = testObj.hat;      // Change this line
var shirtValue = testObj.shirt;    // Change this line
```

78-Accessing Objects Properties with Bracket Notation

```javascript
// Setup
var testObj = {
  "an entree": "hamburger",
  "my side": "veggies",
  "the drink": "water"
};

// Only change code below this line

var entreeValue = testObj["an entree"];   // Change this line
var drinkValue = testObj["the drink"];    // Change this line
```

79-Accessing Objects Properties with Variables

```javascript
// Setup
var testObj = {
  12: "Namath",
  16: "Montana",
  19: "Unitas"
};

// Only change code below this line;

var playerNumber = 16;       // Change this Line
var player = testObj[playerNumber];   // Change this Line
```

80-Updating Object Properties

```javascript
// Example
var ourDog = {
  "name": "Camper",
  "legs": 4,
  "tails": 1,
  "friends": ["everything!"]
};

ourDog.name = "Happy Camper";

// Setup
var myDog = {
  "name": "Coder",
  "legs": 4,
  "tails": 1,
  "friends": ["Free Code Camp Campers"]
};

myDog.name = "Happy Coder";

// Only change code below this line.
```

81-Add New Properties to a JavaScript Object

```javascript
// Example
var ourDog = {
  "name": "Camper",
  "legs": 4,
  "tails": 1,
  "friends": ["everything!"]
};

ourDog.bark = "bow-wow";

// Setup
var myDog = {
  "name": "Happy Coder",
  "legs": 4,
  "tails": 1,
  "friends": ["Free Code Camp Campers"]
};

myDog.bark = "woof";

// Only change code below this line.
```

82-Delete Properties from a JavaScript Object

```javascript
// Example
var ourDog = {
  "name": "Camper",
  "legs": 4,
  "tails": 1,
  "friends": ["everything!"],
  "bark": "bow-wow"
};

delete ourDog.bark;

// Setup
var myDog = {
  "name": "Happy Coder",
  "legs": 4,
  "tails": 1,
  "friends": ["Free Code Camp Campers"],
  "bark": "woof"
};

delete myDog.tails;

// Only change code below this line.
```

83-Using Objects for Lookups

```javascript
// Setup
function phoneticLookup(val) {
  var result = "";

  // Only change code below this line

  var lookup = {
    alpha:"Adams",
    bravo: "Boston",
    charlie: "Chicago",
    delta: "Denver",
    echo: "Easy",
    foxtrot: "Frank"
  };

  result = lookup[val];


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

// Change this value to test
phoneticLookup("charlie");
```

84-Testing Objects for Properties

* 不能用 dot 要用 bra陣列陣列一樣嘛ket notation，有人說是因為資料存在變數裡面(就像是)
* <https://forum.freecodecamp.org/t/freecodecamp-challenge-guide-testing-objects-for-properties/18324/4>

````javascript
// 初始化变量
var myObj = {
  gift: "pony",
  pet: "kitten",
  bed: "sleigh"
};

function checkObj(checkProp) {
  // 请把你的代码写在这条注释以下


  IfInthere = myObj.hasOwnProperty(checkProp);
  result = "";

  if(IfInthere){
    result = myObj[checkProp];
    return result;
  } 
  else {
    result = "Not Found";
    return result;
  }

}

// 你可以修改这一行来测试你的代码
checkObj("gift");


---

85-Manipulating Complex Objects

```js

var myMusic = [
  {
    "artist": "Billy Joel",
    "title": "Piano Man",
    "release_year": 1973,
    "formats": [ 
      "CS", 
      "8T", 
      "LP" ],
    "gold": true
  },
  // Add record here
  {
    "artist": "Chiu",
    "title": "SMS life",
    "release_year": 2017,
    "formats": ["sad", "angry", "helpless"]
  }
];
````

86-Accessing Nested Objects

```javascript
- 有空格的屬性，用

// Setup
var myStorage = {
  "car": {
    "inside": {
      "glove box": "maps",
      "passenger seat": "crumbs"
     },
    "outside": {
      "trunk": "jack"
    }
  }
};

// Only change code below this line

var gloveBoxContents = myStorage.car.inside["glove box"]; // Change this line
```

87-Accessing Nested Arrays

* 物件的屬性存取可以用 dot 或是 bracket notation
* 陣列的內容存取只能用 \[]

```javascript
// Setup
var myPlants = [
  { 
    type: "flowers",
    list: [
      "rose",
      "tulip",
      "dandelion"
    ]
  },
  {
    type: "trees",
    list: [
      "fir",
      "pine",
      "birch"
    ]
  }  
];

// Only change code below this line

var secondTree = myPlants[1].list[1]; // Change this line
```

88-Iterate with JavaScript For Loops

* for (\[initialization]; \[condition]; \[final-expression])

```javascript
// Example
var ourArray = [];

for (var i = 0; i < 5; i++) {
  ourArray.push(i);
}

// Setup
var myArray = [];

for (var i = 1; i < 6; i++){
  myArray.push(i);
}

// Only change code below this line.
```

89-Iterate Odd Numbers With a For Loop

```javascript
// Example
var ourArray = [];

for (var i = 0; i < 10; i += 2) {
  ourArray.push(i);
}

// Setup
var myArray = [];

for (var i = 1; i < 10; i += 2){
  myArray.push(i);
}

// Only change code below this line.
```

90-Count Backwards With a For Loop

```javascript
// Example
var ourArray = [];

for (var i = 10; i > 0; i -= 2) {
  ourArray.push(i);
}

// Setup
var myArray = [];

// Only change code below this line.

for (var i=9; i>0; i-=2){
  myArray.push(i);
}
```


---

# Agent Instructions
This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com.

## Querying This Documentation
If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://ayugioh2003.gitbook.io/free-code-camp-practice/front-end-development-certification/basic-javascript/basic-javascript-90.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.