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JavaScript/Primitive data types/Exercises
Reference material by Wikibooks contributors. This retains its source identity and is not 411 news reporting.
Topic: Primitive Data Types
1. Write a script with the following steps (the 'power'-operator is '**'):
Compute the value of 250. Store it in the variable x1.
Compute the value of 250 + 1. Store it in the variable x2.
Compare x1 with x2. Are they equal?
100% "use strict";
const x1 = 2 ** 50;
const x2 = 2 ** 50 + 1;
alert(x1 == x2); // false
2. Repeat the previous exercise with 260 instead of 250.
100% "use strict";
const x1 = 2 ** 60;
const x2 = 2 ** 60 + 1;
alert(x1 == x2); // true
3. Repeat the previous exercise with 1000 instead of 1.
100% "use strict";
const x1 = 2 ** 60;
const x2 = 2 ** 60 + 1000;
alert(x1 == x2); // false
4. Discuss the results of exercises 1 - 3 with your colleague.
5. Write a script with the following steps:
Compute the value of one divided by three. Store the result in the variable x1.
Show x1.
Multiply x1 by three and store the result in x2.
Show x2. Which value do you expect?
100% "use strict";
const x1 = 1 / 3;
alert(x1);
const x2 = x1 * 3;
alert(x2);
6. Write a script that shows that 5 and 5.0 are identical values.
100% "use strict";
const x1 = 5;
const x2 = 5.0;
alert(x1 == x2);
7. Write a script that
asks the user how old he is: prompt(...)
prompt() always returns a string. To perform the calculation, it's necessary to convert the answer to number parseInt(), parseFloat(), Number()
if his answer is a numeric value, show how often his heart has beaten since his birth (approximately once per second)
else, give a message like "Sorry. We need a numeric value to perform the computation."
100% // a possible solution:
"use strict";
const answer = prompt("How old are you?"); // returns a string
const age = parseFloat(answer); // what's about parseInt() or Number() ?
if (Number.isNaN(age)) { // try other solutions!
alert("Sorry, we need a number to perform the calculation. You typed: '" + answer + "'");
} else {
// about one beat per second
const seconds = age * 365 * 24 * 60 * 60;
alert("Your heart has beaten (approximately) " + seconds + " times since your birth.");
}
8. Create a HTML page for the previous exercise and embed the solution into the HTML. You can refer to this example.
100% <!DOCTYPE html>
<html>
<head>
<title>Seconds</title>
<script>
function go() {
"use strict";
let result;
const answer = document.getElementById("age").value;
const age = Number(answer);
if (Number.isNaN(age)) { // try other solutions!
result = "Sorry, we need a number to perform the calculation. You typed: '" + answer + "'";
} else {
// about one beat per second
const seconds = age * 365 * 24 * 60 * 60;
result = "Your heart has beaten (approximately) " + seconds + " times since your birth.";
}
document.getElementById("result").innerText = result;
}
</script>
</head>
<body>
<h1>How many times has your heart beaten?</h1>
<label>Your age: </label>
<input type="text" id="age">
<button type="button" onclick="go()">GO</button>
<p>
<div id="result">???</div>
</p>
</body>
</html>
{9. What shows the 'alert' statement?
"use strict";
alert(typeof Math.PI);
|type="()"}
- 3.14
- float
+ number
- undefined
- None of the above