Chapter 1 A Quick Dip into JavaS

• JavaScript is a scripting language
• JavaScript is case sensitive
• The name of variables should not match the keywords exactly

Variables and values

• var winner = 2; // a numeric value
• var name = "Duke"; // a string
• var isEligible = false; // booleans
• var losers; // you can also create a variable without an initial value, and assign it a value later

How the while loop works

var scoops = 5;
while (scoops > 0) {
     document.write( "Another scoops!<br>");
     scoops = scoops - 1;
}
document.write( "Life without ice cream isn't the same");

screen print while loop

Making decisions with JavaScript

• a test

if (scoops < 3) {
alert("Ice cream is running low!");
}

• multiple tests

if (scoops >= 5) {
alert("Eat faster, the ice cream is going to melt!");
} else if (scoops < 3) {
alert("Ice cream is running low!");
}

• lots of decisions

if (scoops >= 5) {
alert("Eat faster, the ice cream is going to melt!");
} else if (scoops == 3) {
alert("Ice cream is running low!");
} else if (scoops == 2) { alert("Going once!");
} else if (scoops == 1) { alert("Going twice!");
} else if (scoops == 0) { alert("Gone!");
} else {
alert("Still lots of ice cream left, come and get it.");
}

How do I add code to my page?

屏幕快照 2019-03-31 下午1.31.08.png