NN 2, IE 3
You want to convert a string to all upper- or lowercase letters.
Use the two dedicated String object methods, toLowerCase( ) and toUpperCase( ), for case changes:
var myString = "New York"; var lcString = myString.toLowerCase( ); var ucString = myString.toUpperCase( );
Both methods return modified copies of the original string, leaving it intact. If you want to replace the value of a variable with a case-converted version of the original string (and thus eliminate the original string), reassign the results of the method to the same variable:
myString = myString.toLowerCase( );
Do not, however, redeclare the variable with a var keyword.
Another common need for case conversion is preparing user entries for submission to a database that prefers or requires all uppercase (or all lowercase) letters. You can accomplish this for a user either at time of entry or during batch validation prior to submission. For example, an onchange event handler in a text box can convert the text to all uppercase letters as follows:
<input type="text" name="firstName" id="firstName" size="20" maxlength="25" onchange="this.value = this.value.toUpperCase( )" />
Simply reassign a converted version of the element's value to itself.
Recipe 1.4 for a practical example of case conversion simplifying an important string task.