www.crosswinds.net/~fishcaro/day_J8_online_tutorial.htm
<SCRIPT LANGUAGE="JavaScript">
x = "outside_function";
document.write("Outside the function, x = ",x,"<BR>");
function test() {
x = "inside_function";
document.write("Inside the function, x = ",x,"<BR>");
}
test();
document.write("After the function, x = ",x,"<BR>");
</SCRIPT>
<SCRIPT LANGUAGE="JavaScript">
x = "outside_function";
document.write("Outside the function, x = ",x,"<BR>");
function test() {
var x = "inside_function";
document.write("Inside the function, x = ",x,"<BR>");
}
test();
document.write("After the function, x = ",x,"<BR>");
</SCRIPT>
For each
operator, be able to give an example that illustrates the use
of the operator.
For example: Arithmetic modulus operator: 10%8 gives the result 0 (why?)
Note: the string operator '+' is called the concatenation operator. To concatenate means to connect in a series or chain.
The increment and decrement operators are frequently used in FOR loops: type this code and study what happens.
<SCRIPT LANGUAGE="JavaScript">
for (x=1; x<=10; x++) {
document.write(x," "); }
</SCRIPT>
<SCRIPT LANGUAGE="JavaScript">
for (x=10; x>=1; x--) {
document.write(x," "); }
</SCRIPT>
In general, the pattern x blah= y is a shortcut for x = x blah y .
Thus:
x += y is a shortcut for x = x + y .
x -= y is a shortcut for x = x - y .
x *= y is a shortcut for x = x * y .
x /= y is a shortcut for x = x / y .
x %= y is a shortcut for x = x % y .
Be able to give THREE DIFFERENT ways to take a variable x, add 1 to it, and then store the new value back in x.
Be able to give shortcuts for each of the following operations:
x = x+3;
x = x/3;
x = x*3;
x = x-3;
x = x%3;
A UNARY operator is one that requires only one number. For example, ++ is a unary operator, because a single number is incremented.
Be able to identify each JavaScript operator as either BINARY or UNARY.
Write a function that creates a button that says "My function". When the button is clicked, your function is called. Your function should bring up an alert message that says "Have a nice day!"
SO... get out the Simpletext and your favorite browser! Practice writing this code, WITHOUT LOOKING AT ANYTHING! When you can do it two times in a row, from scratch, without looking, then you're ready for class quizzes and tests!
Test your function on all these lists:
5,7,9,...,275
4,7,10,...,154
-4,0,4,8,...,140
new" operator. This
is why you see:var d = new Date();
var d = new Date();
document.write(d,"<BR>")
document.write(d.getDate(),"<BR>")
document.write(d.getDay(),"<BR>")
(The days are numbered 0 to 6; which day is 0? What number is Wednesday?)document.write(d.getFullYear(),"<BR>")
document.write(d.getHours(),"<BR>")
document.write(d.getMinutes(),"<BR>")
document.write(d.getSeconds(),"<BR>")
document.write(d.getMonth(),"<BR>")
(condition) ? value1: value2; ret = (x==5) ? "five": "not five" document.write( (x==5) ? "five": "not five" );
x = 5;
document.write( (x==5) ? "five ": "not five " );
document.write( (x==4) ? "four ": "not four " );
The basic if/else statement is useful for executing TWO pieces of code: one if a statement is true,
the other if a statement is false. But when you want to do LOTS of different things, use
the structure that is illustrated in the following example:
if (n<0) {
// When n is less than zero, do this stuff.
}
else if (n>=0 && n<2) {
// When n is between 0 and 2, do this stuff.
}
else if (n>=2 && n<3) {
// When n is between 2 and 3, do this stuff. And on and on and on.
}
k=1; // initialization
while (k<=5) { // the code block will be executed while k is less than or equal to 5
document.write(k,"<BR>");
k++; // increment k
}
i=5;
while (i<5) {
document.write(i,"<BR>"); i--;
}
i=5;
do {
document.write(i,"<BR>"); i--;
}
while (i<5);
i=1; //
while (i<=5) {
document.write(i,"<BR>");
i++;
}
for (i=1; i<=5; i++) {
document.write(i,"<BR>");
}
string = "Carol";
document.write(string.fontsize(3));
x = 5;
x=5;
x= 5;