JavaScript by Example: JavaScript Core Objects. Pt. 2

<html><head><title>The Prototype Property</title>

// Customize String Functions

1 function ucLarge(){

var str=this.bold().fontcolor("white").

toUpperCase().fontsize("22");

return( str);

}

2 String.prototype.ucL=ucLarge;

</script>

</head>

3 var string="Watch Your Step!!";

4 document.write(string.ucL()+"<br>");

</script>

</body></html>

The ucLarge() function is defined. Its purpose is to generate and return an uppercase, bold, white font, with a point size of 22.

The prototype property allows you to customize an object by adding new properties and methods. The name of the customized method is ucL, which is the name of a new method that will be used by the String object. It is assigned the name (without parentheses) of the function ucLarge(), that performs the method's actions and returns a value.
A new string is created.
The prototyped method, ucL(), is applied to the String object, str. It will modify the string as shown in the output in Figure 9.22
.

String object (HTML) methods.
Method	Formats as HTML
String.anchor(Name)	<a name="Name">String</a>
String.big()	<big>String</big>
String.blink()	<blink>String</blink>
String.bold()	<b>String</b>
String.fixed()	<tt>String</tt>
String.fontcolor(color)	<font color="color">String</font> e.g., <font color="blue">String</font>
String.fontsize(size)	<font size="size">String</font> e.g., <font size="+2">String</font>
String.italics()	<i>String</i>
String.link(URL)	<a href="URL">String</a> e.g., <a href="http://www.ellieq.com">String</a>
String.small()	<small>String</small>
String.strike()	<strike>String</strike> (puts a line through the text)
String.sub()	<sub>String</sub> (creates a subscript)
String.sup()	<sup>String</sup> (creates a superscript)

String object (HTML) methods.

Method

Formats as HTML

String.anchor(Name)

<a name="Name">String</a>

String.big()

<big>String</big>

String.blink()

<blink>String</blink>

String.bold()

<b>String</b>

String.fixed()

<tt>String</tt>

String.fontcolor(color)

<font color="color">String</font>

e.g., <font color="blue">String</font>

String.fontsize(size)

<font size="size">String</font>

e.g., <font size="+2">String</font>

String.italics()

<i>String</i>

String.link(URL)

<a href="URL">String</a>

e.g., <a href="http://www.ellieq.com">String</a>

String.small()

<small>String</small>

String.strike()

<strike>String</strike> (puts a line through the text)

String.sub()

<sub>String</sub> (creates a subscript)

String.sup()

<sup>String</sup> (creates a superscript)


<html> <head><title>String object</title> </head> <body bgcolor="yellow"> <font size="+1" face="arial"> <h2>Working with String Objects:</h2> <script language="JavaScript"> 1 var str1 = new String("Hello world!"); // Use a String constructor 2 var str2 = "It's a beautiful day today."; document.write(str1) + "<br>"; 3 document.write(str1.fontcolor("blue")+"<br>"); 4 document.write(str1.fontsize(8).fontcolor("red"). bold()+"<br>"); 5 document.write(str1.big()+ "<br>"); 6 document.write("Good-bye, ".italics().bold().big() + str2 + "<br>"); </script> </body></html>

<html>

<head><title>String object</title>

</head>

<h2>Working with String Objects:</h2>

1 var str1 = new String("Hello world!"); // Use a String constructor

2 var str2 = "It's a beautiful day today.";

document.write(str1) + "<br>";

3 document.write(str1.fontcolor("blue")+"<br>");

4 document.write(str1.fontsize(8).fontcolor("red").

bold()+"<br>");

5 document.write(str1.big()+ "<br>");

6 document.write("Good-bye, ".italics().bold().big() +

str2 + "<br>");

</script>

</body></html>


A String object is created with the String() constructor.
A string primitive is created the literal way. The fontcolor() method is used to change the color of the string to blue. This method emulates the HTML tag, <font color="blue">. The fontsize(), fontcolor(), and bold() methods are used as properties of the string. The HTML method is concatenated to the string "Good-bye, " causing it to be displayed in italic, bold, big text. (See Figure 9.23.)

A String object is created with the String() constructor.

A string primitive is created the literal way.
The fontcolor() method is used to change the color of the string to blue. This method emulates the HTML tag, <font color="blue">.
The fontsize(), fontcolor(), and bold() methods are used as properties of the string.
The HTML method is concatenated to the string "Good-bye, " causing it to be displayed in italic, bold, big text. (See Figure 9.23.)

Methods for string manipulation.
Method	What it Does
charAt(index)	Returns the character at a specified index position
charCodeAt(index)	Returns the Unicode encoding of the character at a specified index position
concat(string1, ..., stringn)	Concatenates string arguments to the string on which the method was invoked
fromCharCode(codes)	Creates a string from a comma-separated sequence of character codes
indexOf(substr, startpos)	Searches for first occurrence of substr starting at startpos and returns the startpos(index value) of substr
lastIndexOf(substr, startpos)	Searches for last occurrence of substr starting at startpos and returns the startpos (index value) of substr
replace(searchValue, replaceValue)	Replaces searchValue with replaceValue
search(regexp)	Searches for the regular expression and returns the index of where it was found
slice(startpos, endpos)	Returns string containing the part of the string from startpos to endpos
split(delimiter)	Splits a string into an array of words based on delimiter
substr(startpos, endpos)	Returns a subset of string starting at startpos up to, but not including, endpos
toLocaleLowerCase()	Returns a copy of the string converted to lowercase
toLocaleUpperCase()	Returns a copy of the string converted to uppercase
toLowerCase()	Converts all characters in a string to lowercase letters
toString()	Returns the same string as the source string
toUpperCase()	Converts all characters in a string to uppercase letters
valueOf	Returns the string value of the object