Difference between revisions of "Removing Special Characters"

Revision as of 17:23, 30 April 2009

The following technique can be used to prevent a user from entering special characters in designated form fields.

Special characters can cause problems, particularly when the data is exported to other applications.

For example, if you wish to export the data to Microsoft Excel, any text fields with ampersands (&) or quotation marks (" or ') often cause formatting issues for Excel.

Procedure:

Include the following code in the HTML Tag box of the custom field you wish to restrict:

onchange="javascript:this.value=this.value.replace(/[Search Expression]/flag,' New String ');"

where

• Search Expression specifies a string value to find.
• New String specifies the replacement string.
• flag is a command line switch used to control outcome of the replace operation.

If you want the replacement to happen actively while the user is typing into the field use onKeyup instead of onChange.

Options

For Search Expression you can use

• \W = Matches any character that is not a character from the basic Latin alphabet, an integer, or the underscore.
• \w = Matches any alphanumeric character from the basic Latin alphabet, including the underscore. Equivalent to [A-Za-z0-9_]
• \D = Matches any character that is not an integer.
• \d = Matches all integers. Equivalent to [0-9]
• \0 = NULL character
• \s = Matches a single white space character
• [xyz]= A character set. Matches any one of the enclosed characters. You can specify a range of characters by using a hyphen.

       For example, [abcd] is the same as [a-d]. They match the 'b' in "brisket" and the 'c' in "ache". 

• Any individual character can be specified within the square brackets except double quote " which has special meaning.
• If you wish to include the backslash \ or closing square bracket ] you must precede them with a backslash:

For Flag the following options are available:

• g = global match
• i = ignore case

Using onChange will replace the characters as soon as the user clicks away from current field, or hits Save.
Using onKeyup will replace the characters as soon as they are typed.

Examples

1. To remove all characters that aren't part of the basic Latin alphabet and 0-9 (such as . , & ; : ~ ! @ # $ % ^ & * ( ) + " ' including the space key) and immediately replace them with an underscore (_):

onkeyup="javascript:this.value=this.value.replace(/[\W]/g,'_');"

2. The following code will look for # [ $ ] and \ and replace them with an underscore (_) once the user has clicked away from the field:

onchange="javascript:this.value=this.value.replace(/[#[$\]\\@]/g,'_');"

Note: if you also want to replace double quotes you can omit the double quotes around the javascript statement:

onchange=javascript:this.value=this.value.replace(/['@#&"]/g,'_');

3. To restrict user to only enter Integers write this code in the HTML tag box:

onkeyup="javascript:this.value=this.value.replace(/[\D]/g,);"