Extra Practice

Remember: Learning to program takes practice! It helps to see concepts over and over, and it's always good to try things more than once. We learn much more the second time we do something. Use the exercises and additional self-checks below to practice.

1. Data Types and Variable Assignment

let score = 42;

let quote = "Move fast and break stuff.";

let fruits = ['apple', 'orange', 'pear'];

let foo,
    bar,
    baz;

let stopLoop = false;

let userRegistered = true;

What is the name of the String variable above?

fruits score quote foo The String variable is quote.

What Data Type is score?

String Number Boolean Array The score variable is a Number.

What does fruits.length equal?

2 4 3 true fruits.length equals 3.

What are foo, bar, and baz equal to?

0 '' null undefined The variables foo, bar, and baz are equal to undefined because they have been declared but not initialized.

What is it called when we name a variable without setting a variable (as with foo, bar, and baz in the code above)?

declaration initialization casting definition When we name a variable without assigning a value, we are "declaring" that variable for usage later. Its value will be undefined until it is initialized.

What Data Types are stopLoop and userRegistered?

String Array Number Boolean The variable baz is equal to undefined because we cannot multiply two Strings.

2. JSON Interpretation

let weatherData = {
    "city": {
        "id": 5809844,
        "name": "Seattle",
        "coord": {
            "lon": -122.3321,
            "lat": 47.6062
        },
        "country": "US",
    },
    "list": [
        {
            "dt": 1500148800,
            "temp": {
                "day": 74.05,
                "min": 55.96,
                "max": 75.09,
                "night": 55.96,
                "eve": 69.6,
                "morn": 68.9
            },
            "pressure": 1024.13,
            "humidity": 51,
            "weather": [
                {
                    "id": 800,
                    "main": "Clear",
                    "description": "sky is clear",
                    "icon": "01d"
                }
            ],
            "speed": 5.17,
            "deg": 222,
            "clouds": 0
        },
        {
            "dt": 1500235200,
            "temp": {
                "day": 67.3,
                "min": 55.78,
                "max": 68.94,
                "night": 56.08,
                "eve": 65.71,
                "morn": 55.78
            },
            "pressure": 1026.81,
            "humidity": 57,
            "weather": [
                {
                    "id": 800,
                    "main": "Clear",
                    "description": "sky is clear",
                    "icon": "01d"
                }
            ],
            "speed": 3.38,
            "deg": 353,
            "clouds": 0
        },
        {
            "dt": 1500321600,
            "temp": {
                "day": 69.85,
                "min": 52.63,
                "max": 70.54,
                "night": 52.63,
                "eve": 66.49,
                "morn": 58.32
            },
            "pressure": 1019.85,
            "humidity": 51,
            "weather": [
                {
                    "id": 801,
                    "main": "Clouds",
                    "description": "few clouds",
                    "icon": "02d"
                }
            ],
            "speed": 6.71,
            "deg": 357,
            "clouds": 12
        }
    ]
}

The data above represents a three-day weather forecast for Seattle, WA. Use this data structure to answer the questions below.

What is the Data Type of the weatherData.city property above?

String Number Boolean Object Array weatherData.city is an Object.

What Data Type is weatherData.list?

String Number Boolean Object Array weatherData.list is an Array.

What does weatherData.list.length equal?

2 4 3 true weatherData.length equals 3.

What does weatherData.list[1].humidity equal?

58.32 51 57 75.3 weatherData.list[1].humidity equals 57.

What does weatherData.list[0].temp.eve equal?

56.7 69.6 78.3 82.1 weatherData.list[0].temp.eve equals 69.6.

What is the Data Type of weatherData.list[2].weather[0].main?

String Number Boolean Object Array weatherData.list[0].weather[0].main is a String.

What is the Data Type of weatherData.list[2].weather?

String Number Boolean Object Array weatherData.list[0].weather is an Array.

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