Jan 26, 2018
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Variables can't start with a number. You can define any kind of datatype with var:
var myName = "Tom";
MATH.E
MATH.PI
MATH.log()
MATH.sqrt()
if ( ) {
..
} else if ( ) {
..
}
Ternary Operator assigns a value based on a condition as: "(condition) ? iftrue : ifFalse":
var canIVote = (age >= 18) ? true : false;
switch (age) {
case 5 :
document.write ("Go to Kindergarten<br />");
break;
case 7 :
document.write ("Go to 1st Grade<br />");
break;
default :
document.write ("Subtract 5 from your age<br />");
}
do {
var guess = prompt ("Guess a number between 1 and 20");
} while (guess != 15)
for (j = 0; j <= 20; j++) {
if ((j % 2) == 0) {
continue;
}
if (j == 15) {
break;
}
}
for (k in customer) {
document.write (customer[k], "<br />");
}
Convert strings to numbers:
document.write ("Converted String : ", Number("3.14"), "<br />");
document.write ("Random # (1-10) = ", Math.floor ((Math.random() * 10) + 1), "<br/>");
A string is a bunch of individual characters.
var randStr = "A long " + "string that " + "goes on and on";
Get the length of a string:
document.write ("String Length : ", randStr.length + "<br/>");
Slice and substr:
document.write (randStr.slice(19, 23) + "<br/>");
document.write (randStr.slice(19) + "<br/>");
document.write (randStr.substr(19, 4) + "<br/>");
Replace a string:
document.write (randStr.replace("and on", "forever") + "<br/>");
Get characters at index:
document.write ("At Index 2 : ", randStr.charAt (2) + "<br/>");
Split:
var randStrArray = randStr.split (" ");
Trim:
randStr = randStr.trim ();
Converting to uppercase or to lowercase:
document.write (randStr.toUpperCase() + "<br/>");
document.write (randStr.toLowerCase() + "<br/>");
Styling a string:
var strToStyle = "Random String";
document.write ("Big : ", strToStyle.big(), "<br />");
document.write ("Bold : ", strToStyle.bold(), "<br />");
document.write ("Font Color : ", strToStyle.fontcolor("blue"), "<br />");
document.write ("Font Size : ", strToStyle.fontsize("8em"), "<br />");
document.write ("Italics : ", strToStyle.italics(), "<br />");
document.write ("Google : ", strToStyle.link("http://google.com"), "<br />");
document.write ("Small : ", strToStyle.small(), "<br />");
document.write ("Strike : ", strToStyle.strike(), "<br />");
document.write ("Sub : ", strToStyle.sub(), "<br />");
document.write ("Sup : ", strToStyle.sup(), "<br />");
Arrays have variable sizes and can contain multiple types in JS.
var tomSmith = ["Tom Smith", "123 Main", 120.50];
Add an item:
tomSmith[3] = "tsmith@aol.com";
Delete an index:
delete tomSmith[3];
Sort an array:
tomSmith.sort ();
Concat strings:
var combinedArray = numbers.concat (tomSmith);
Push and pop:
tomSmith.pop ();
tomSmith.push ("555-1212", "US");
Shift the first item:
tomSmith.shift ();
var curDate = new Date ();
document.write ("Date : ", curDate.getDate (), "<br />");
document.write ("Month : ", curDate.getMonth (), "<br />");
document.write ("Day : ", curDate.getDay (), "<br />");
document.write ("Year : ", curDate.getFullYear (), "<br />");
document.write ("Time : ", curDate.getHours (), ":", curDate.getMinutes (),
":", curDate.getSeconds (), ":", curDate.getMilliseconds (), "<br />");
var myBD = new Date ("December 21, 2015");
Local variables defined in functions can't be accessed outside of the function.
function inArray (arrayToCheck, value) {
..
}
function times2 (num) {
var var2 = 2;
return num * var2;
}
var custArray = ["Tom", "Bob", "Sally", "Sue"];
var getCust = function (index) {
if (index > custArray.length) {
throw new RangeError ("Index must be >= 0 and <= " + custArray.length );
} else {
return custArray[index];
}
}
try {
document.write("Customer : ", getCust(5), "<br />");
} catch (ex) {
if (ex instanceof RangeError) {
document.write(ex.message + "<br />");
}
}
var object = function ( <parameters> ) {
var self = {};
self.<property> = <property>;
self.<function> = function () {
..
}
var <function> = self.<function> ();
return self;
}
To create an object do:
new object(<parameters>);
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