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JavaScript For...In Statement

JavaScript For...In Statement The for...in statement loops through the elements of an array or through the properties of an object. Syntax. for ( variable in object )   {   code to be executed   }. Note: The code in the body of the for...in loop is executed once for each element/property.

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JavaScript For...In Statement

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  1. JavaScript For...In Statement The for...in statement loops through the elements of an array or through the properties of an object. Syntax for (variable in object)  {  code to be executed  } Note: The code in the body of the for...in loop is executed once for each element/property.

  2. <html> <body> <script type="text/javascript"> var x; var mycars = new Array(); mycars[0] = "Saab"; mycars[1] = "Volvo"; mycars[2] = "BMW"; for (x in mycars) { document.write(mycars[x] + "<br />"); } </script> </body> </html> SaabVolvoBMW

  3. Events By using JavaScript, we have the ability to create dynamic web pages. Events are actions that can be detected by JavaScript. Every element on a web page has certain events which can trigger a JavaScript. For example, we can use the onClick event of a button element to indicate that a function will run when a user clicks on the button. We define the events in the HTML tags. Examples of events: A mouse click A web page or an image loading Mousing over a hot spot on the web page Selecting an input field in an HTML form Submitting an HTML form A keystroke Note: Events are normally used in combination with functions, and the function will not be executed before the event occurs!

  4. JavaScript Array Object Array Object Properties

  5. Array Object Methods

  6. <html> <body> <script type="text/javascript"> var fruits = ["Banana", "Orange", "Apple", "Mango"]; document.write("Original length: " + fruits.length); document.write("<br />"); fruits.length=5; document.write("New length: " + fruits.length); </script> </body> </html> Original length: 4New length: 5

  7. <html> <body> <script type="text/javascript"> var fruits = ["Banana", "Orange", "Apple", "Mango"]; document.write(fruits.push("Kiwi") + "<br />"); document.write(fruits.push("Lemon","Pineapple") + "<br />"); document.write(fruits); </script> </body> </html> 57Banana,Orange,Apple,Mango,Kiwi,Lemon,Pineapple

  8. <html> <body> <script type="text/javascript"> var fruits = ["Banana", "Orange", "Apple", "Mango"]; document.write(fruits.reverse()); </script> </body> </html> Mango,Apple,Orange,Banana

  9. <html> <body> <script type="text/javascript"> var fruits = ["Banana", "Orange", "Apple", "Mango"]; document.write(fruits.shift() + "<br />"); document.write(fruits + "<br />"); document.write(fruits.shift() + "<br />"); document.write(fruits); </script> </body> </html> BananaOrange,Apple,MangoOrangeApple,Mango

  10. Insert Special Characters

  11. Return the length of a stringHow to return the length of a string. <html> <body> <script type="text/javascript"> var txt = "Hello World!"; document.write(txt.length); </script> </body> </html> 12

  12. Style stringsHow to style strings. <html><body> <script type="text/javascript"> var txt = "Hello World!"; document.write("<p>Big: " + txt.big() + "</p>"); document.write("<p>Small: " + txt.small() + "</p>"); document.write("<p>Bold: " + txt.bold() + "</p>"); document.write("<p>Italic: " + txt.italics() + "</p>"); document.write("<p>Fixed: " + txt.fixed() + "</p>"); document.write("<p>Strike: " + txt.strike() + "</p>"); document.write("<p>Fontcolor: " + txt.fontcolor("green") + "</p>"); document.write("<p>Fontsize: " + txt.fontsize(6) + "</p>"); document.write("<p>Subscript: " + txt.sub() + "</p>"); document.write("<p>Superscript: " + txt.sup() + "</p>"); document.write("<p>Link: " + txt.link("http://www.w3schools.com") + "</p>"); document.write("<p>Blink: " + txt.blink() + " (does not work in IE, Chrome, or Safari)</p>"); </script> </body> </html>

  13. The toLowerCase() and toUpperCase() methodsHow to convert a string to lowercase or uppercase letters. <html> <body> <script type="text/javascript"> var txt="Hello World!"; document.write(txt.toLowerCase() + "<br />"); document.write(txt.toUpperCase()); </script> </body> </html> hello world!HELLO WORLD!

  14. The indexOf() methodHow to return the position of the first found occurrence of a specified value in a string. <html> <body> <script type="text/javascript"> var str="Hello world!"; document.write(str.indexOf("d") + "<br />"); document.write(str.indexOf("WORLD") + "<br />"); document.write(str.indexOf("world")); </script> </body> </html> 10-16

  15. What is an Array? An array is a special variable, which can hold more than one value, at a time. If you have a list of items (a list of car names, for example), storing the cars in single variables could look like this:

  16. Create an Array An array can be defined in three ways. The following code creates an Array object called myCars: 1: 2: 3:

  17. Access an Array You can refer to a particular element in an array by referring to the name of the array and the index number. The index number starts at 0. The following code line: will result in the following output:

  18. Modify Values in an Array To modify a value in an existing array, just add a new value to the array with a specified index number: Now, the following code line: will result in the following output:

  19. Create a Boolean Object The Boolean object represents two values: "true" or "false". The following code creates a Boolean object called myBoolean: Note: If the Boolean object has no initial value or if it is 0, -0, null, "", false, undefined, or NaN, the object is set to false. Otherwise it is true (even with the string "false")! All the following lines of code create Boolean objects with an initial value of false: var myBoolean=new Boolean();var myBoolean=new Boolean(0);var myBoolean=new Boolean(null);var myBoolean=new Boolean("");var myBoolean=new Boolean(false);var myBoolean=new Boolean(NaN);

  20. <html> <body> <script type="text/javascript"> var b1=new Boolean( 0); var b2=new Boolean(1); var b3=new Boolean(""); var b4=new Boolean(null); var b5=new Boolean(NaN); var b6=new Boolean("false"); document.write("0 is boolean "+ b1 +"<br />"); document.write("1 is boolean "+ b2 +"<br />"); document.write("An empty string is boolean "+ b3 + "<br />"); document.write("null is boolean "+ b4+ "<br />"); document.write("NaN is boolean "+ b5 +"<br />"); document.write("The string 'false' is boolean "+ b6 +"<br />"); </script> </body> </html> 0 is boolean false1 is boolean trueAn empty string is boolean falsenull is boolean falseNaN is boolean falseThe string 'false' is boolean true

  21. round()How to use round(). random()How to use random() to return a random number between 0 and 1. max()How to use max() to return the number with the highest value of two specified numbers. min()How to use min() to return the number with the lowest value of two specified numbers.

  22. <html> <body> <script type="text/javascript"> document.write(Math.round(0.60) + "<br />"); document.write(Math.round(0.50) + "<br />"); document.write(Math.round(0.49) + "<br />"); document.write(Math.round(-4.40) + "<br />"); document.write(Math.round(-4.60)); </script> </body> </html> 110-4-5

  23. <html> <body> <script type="text/javascript"> //return a random number between 0 and 1 document.write(Math.random() + "<br />"); //return a random integer between 0 and 10 document.write(Math.floor(Math.random()*11)); </script> </body> </html> 0.84424412382979266

  24. <html> <body> <script type="text/javascript"> document.write(Math.max(5,10) + "<br />"); document.write(Math.max(0,150,30,20,38) + "<br />"); document.write(Math.max(-5,10) + "<br />"); document.write(Math.max(-5,-10) + "<br />"); document.write(Math.max(1.5,2.5)); </script> </body> </html> 1015010-52.5

  25. <html> <body> <script type="text/javascript"> document.write(Math.min(5,10) + "<br />"); document.write(Math.min(0,150,30,20,38) + "<br />"); document.write(Math.min(-5,10) + "<br />"); document.write(Math.min(-5,-10) + "<br />"); document.write(Math.min(1.5,2.5)); </script> </body> </html> 50-5-101.5

  26. Math Object Properties

  27. Math Object Methods

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