JavaScript Programming

1. When the statement that follows is executed, JavaScript

var rate = parseFloat(document.getElementById("rate").value);

a.	executes the getElementById method, executes the value method of the resulting object, and executes the parseFloat method on that value
b.	executes the getElementById method, gets the value property of the resulting object, and executes the parseFloat method on that value
c.	executes the parseFloat method, executes the getElementById method, and executes the value method of the resulting object
d.	executes the parseFloat method, executes the getElementById method, and gets the value property of the resulting object

2. The following code

var display_error = function(message) {

alert("Error: " + message);

}

a.	creates a function named display_error.
b.	creates a function and stores it in a variable named display_error.
c.	creates a function named message.
d.	calls a function named message.

Code example 4-1

var add = function( x, y ) {

return ( x + y );

}

alert( add (5, 3) );

3. (Refer to code example 4-1) The function in this example

a.	accepts 2 parameters and returns 2 values.
b.	accepts 2 parameters and returns 1 value.
c.	accepts 2 parameters and does not return a value.
d.	does not accept a parameter and returns 1 value.

4. (Refer to code example 4-1) The alert method in this example

a.	displays a dialog box with a value of 8.
b.	displays a dialog box with a value of 5, 3.
c.	displays a dialog box with a value of x + y.
d.	does not display a dialog box.

4. Which of the following is NOT one of the three testing phases of a JavaScript application?

a.	Trying to make the application fail
b.	Using the developer tools to check the DOM
c.	Testing the application with valid data
d.	Testing the application with invalid data

5. The code that follows has a bug in it because the second use of the variable named salesTax is spelled with all lowercase letters (salestax).

var calculateTax = function(subtotal,taxRate) {

var salesTax = subtotal * taxRate;

salestax = parseFloat(salesTax.toFixed(2));

return salesTax;

}

6. Assuming that there are no other problems and that youre using strict mode, what will happen when this code is executed?

a.	salesTax will contain the right value, but it wont be rounded
b.	an error will occur because salestax hasnt been declared
c.	salestax will contain the rounded sales tax value
d.	salesTax will contain null when it is returned

7. When you test an application with Chromes developer tools and a breakpoint is reached, you can view the current data by

a.	moving the mouse pointer over the name of a variable in the Sources panel
b.	clicking in the bar to the left of a statement that uses an arithmetic expression
c.	hovering the mouse pointer over a variable name in the Elements panel
d.	looking up the variable in the names table in the Console panel

8. If a numerical operation returns a number greater than the largest possible JavaScript value, it returns

a.	NaN
b.	-NaN
c.	Infinity
d.	-Infinity

9. What method of the Number object returns a string with the number rounded to the specified number of decimal places?

a.	the toString method
b.	the round method
c.	the toPrecision method
d.	the toFixed method

10. What text does the following code display in a dialog box?

alert("The file is in \"C:\\My Documents\"");

a.	The file is in C:\My Documents
b.	The file is in "C:\My Documents"
c.	The file is in C:\\My Documents\
d.	The file is in "C:\\My Documents\"