<HTML>
<HEAD>
<TITLE>Throwing a Custom Error Object Exception - Happy Codings :-) JavaScript Code Examples</TITLE>
<SCRIPT LANGUAGE="JavaScript">
var letters = new Array("A","B","C","D","E")
function getErrorObj(msg) {
    var err = new Error(msg)
    // take care of IE5/5.5
    if (!err.message) {
        err.message = msg
    }
    err.name = "MY_ERROR"
    return err
}
function getLetter(fld) {
    try {
    var inp = parseInt(fld.value, 10)
        if (isNaN(inp)) {
            throw getErrorObj("Entry was not a number.")
        }
        if (inp < 1 || inp > 5) {
            throw getErrorObj("Enter only 1 through 5.")
        }
        fld.form.output.value = letters[inp]
    }
    catch (e)  {
        switch (e.name) {
            case "MY_ERROR" :
                alert(e.message)
                fld.form.output.value = ""
                fld.focus()
                fld.select()
                break
            default :
                alert("Reload the page and try again.")
        }
    }
}
</SCRIPT>
</HEAD>
<BODY>
<H1>Throwing a Custom Error Object Exception</H1>
<HR>
<FORM>
Enter a number from 1 to 5: 
<INPUT TYPE="text" NAME="input" SIZE=5>
<INPUT TYPE="button" VALUE="Get Letter" onClick=getLetter(this.form.input)>
Matching Letter is:<INPUT TYPE="text" NAME="output" SIZE=5>
</FORM>
</BODY>
</HTML>