JavaScript by Example: JavaScript Core Objects. Pt. 2

var string_name = "string of text";

var string_name = new String("string of text");

Example:

var title="JavaScript by Example";

var title=new String("JavaScript by Example");

<html><head><title>The String Object</title></head>

<h2>Primitive and String Objects</h2>

1 var first_string = "The winds of war are blowing.";

2 var next_string = new String("There is peace in the valley.");

3 document.write("The first string is of type<em> "+

typeof(first_string));

document.write(".</em><br>The second string is of type<em> "+

4 typeof(next_string) +".<br>");

</script>

</body>

</html>

The String() constructor and the new keyword are used to create a String object. This is the explicit way of creating a string.
The typeof operator demonstrates that the first string, created the literal, implicit way, is a String data type.
The typeof operator demonstrates that this string, created with the String() constructor, is an object type. Either way, when properties and methods are applied to a string, it is treated as a String object. (See Figure 9.20.)

String object properties.
Property	What It Does
length	Returns the length of the string in characters
prototype	Extends the definition of the string by adding properties and methods

Property

What It Does

length

Returns the length of the string in characters

prototype

Extends the definition of the string by adding properties and methods


<html><head><title>The String Object</title></head> <body bgColor="lightblue"> <font face="arial" size=+1> <h3>Length of Strings</h3> <script language="JavaScript"> 1 var first_string = "The winds of war are blowing."; var next_string = new String("There is peace in the valley."); 2 document.write("\""+first_string +"\" contains "+ first_string.length + " characters."); 3 document.write("<br>\""+ next_string+"\" contains "+ next_string.length+" characters.<br>"); document.write("<font size=-1><em>...not to imply that war is equal to peace...<br>"); </script> </body> </html>

<html><head><title>The String Object</title></head>

<h3>Length of Strings</h3>

1 var first_string = "The winds of war are blowing.";

var next_string = new String("There is peace in the valley.");

2 document.write("\""+first_string +"\" contains "+

first_string.length + " characters.");

3 document.write("<br>\""+ next_string+"\" contains "+

next_string.length+" characters.<br>");

document.write("<font size=-1><em>...not to imply that war is

equal to peace...<br>");

</script>

</body>

</html>


Two strings are created, one the literal way (a string primitive) and the other with the constructor method (a String object).
The length property is applied to the first string. When the property is applied to a literal string, it is temporarily converted to an object, and then after the operation, it is reverted back to a string primitive. The length property is applied to the second string, a String object. (It is just a coincidence that both strings are of the same length.) (See Figure 9.21.)

The length property is applied to the first string. When the property is applied to a literal string, it is temporarily converted to an object, and then after the operation, it is reverted back to a string primitive.
The length property is applied to the second string, a String object. (It is just a coincidence that both strings are of the same length.) (See Figure 9.21.)