JavaScript/Self Test

You can test yourself by answering the following questions. When in doubt, you should undertake a test in your development environment (editor, IDE, browser). So it's also a test of whether you have installed all the necessary tools to execute the examples of the Wikibook.

Introduction

1 Inside which HTML element do you put the JavaScript code?

	<javascript>
	<source>
	<script>
	<scripting>
	None of the above.

2 Does this sequence of statements lead to an error?

let x = 0;
x = 1;
x = 'one';

	Yes
	No

Syntax and Semantic

1 Is there a syntax error?

let x = 1:

	Yes
	No

2 Is there a syntax error?

let x = 1;
let y = 2;
x+y = 3;

	Yes
	No

3 Which line contains a syntax error?

/* 1 */ let x = 1;
/* 2 */ let y = 1;
/* 3 */ let x = 1, y = 1;
/* 4 */ let x, y = 1;

	Line 1
	Line 2
	Line 3
	Line 4
	None of the above

4 Which lines contain a syntax error?

/* 1 */ let firstName_1 = "Michael";
/* 2 */ let firstName_2 = 'Michael';
/* 3 */ let firstName_4 = 'Mikhaïl';
/* 4 */ let firstName_5 = "Михаил";

	Line 1
	Line 2
	Line 3
	Line 4
	None of the above

5 Which line leads to an error message?

/* 1 */ let x = 1;
/* 2 */ const y = 2;
/* 3 */ x = 3;
/* 4 */ y = 4;

	Line 1
	Line 2
	Line 3
	Line 4
	None of the above

6 Which line leads to an error message?

/* 1 */ let x = 1;
/* 2 */ x = 2 + 3(4 + 5);
/* 3 */ x = 3;
/* 4 */ x = -x;

	Line 1
	Line 2
	Line 3
	Line 4
	None of the above

7 Which line(s) leads to an error message?

/* 1 */ let x = [1, 2];
/* 2 */ let x = [[1], [2]];
/* 3 */ let x = [[1, 2], [3, 4]];
/* 4 */ let x = [[[1], [2]], [[3], [4]]];
/* 5 */ let x = [1], [2];
/* 6 */ let x = [1, '2'];

	Line 1
	Line 2
	Line 3
	Line 4
	Line 5
	Line 6
	None of the above

8 Is there a syntax error?

"use strict";
let persons = ['Alice', 'Bert', 'Caesar'];
for (let i = 0, i < persons.length, i++) {
  alert(persons[i]);
} //

	Yes
	No

9 Which line contains a syntax error?

/* 1 */ alert("1 + 2 = " + 3);
/* 2 */ alert("1 + 2 = " + "3");
/* 3 */ alert("1 + 2 = " 3)
/* 4 */ alert(1 + 2 == 3)

	Line 1
	Line 2
	Line 3
	Line 4
	None of the above

Type Conversion

1 Which message(s) will not be shown?

let x = 1, y = 2, z = '2';
alert(x + y);
alert(x + z);
alert(x - z);

	3
	12
	-1
	All will be shown.

2 What message(s) will not be shown?

let x = 1;
alert(x);
alert(x = 5);
alert(x == '5');
alert(x === 5);

	Error Message
	true
	false
	5
	1

Loops

1 What will be the result in sum?

"use strict";
let sum = 0;
for (let i = 1; i < 5; i++) {
  sum = sum + i;
} //
alert(sum);

The result in sum will be .

2 What will be the result in sum?

"use strict";
let sum = 0;
for (let i = 0; i < 5; i++) {
  for (let j = 10; j >= 0; j--) {
    if (i === j) {
      sum = sum + i - j + 1;
    } //
  } //
} //
alert(sum);

The result in sum will be .

3 Is there a syntactical error?

"use strict";
let sum = 0;
for (let i = 0; i < 5; i++)
  for (let j = 10; j >= 0; j--) {
    if (i === j) {
      sum = sum + i - j + 1;
    } //
  } //
} //
alert(sum);

	Yes
	No

4 What will be the result?

"use strict";
let sum = 0;
for (let i = 0; i = 3; i++) {
  sum = sum + i;
} //
alert(sum);

	0
	6
	Infinite loop
	None of the above