Java script validations

Javascript Form Validation

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Put all of the code examples  between these script tags.

---

<script language="JavaScript">
<!--

//-->
</script>

E-Mail format checking script. if (document.formname.fieldname.value.length >0) { i=document.formname.fieldname.value.indexOf("@") j=document.formname.fieldname.value.indexOf(".",i) k=document.formname.fieldname.value.indexOf(",") kk=document.formname.fieldname.value.indexOf(" ") jj=document.formname.fieldname.value.lastIndexOf(".")+1 len=document.formname.fieldname.value.length if ((i>0) && (j>(1+1)) && (k==-1) && (kk==-1) && (len-jj >=2) && (len-jj<=3)) { } else { alert("Please enter an exact email address.\n" + document.formname.fieldname.value + " is invalid."); return false; } }

Check if field has special characters. var iChars = "!@#$%^&*()+=-[]\\\';,./{}|\":<>?"; for (var i = 0; i < document.formname.fieldname.value.length; i++) { if (iChars.indexOf(document.formname.fieldname.value.charAt(i)) != -1) { alert ("Your username has special characters. \nThese are not allowed.\n Please remove them and try again."); return false; } }

Check if certian radio buttons have not been selected. if (!document.formname.fieldname[0].checked && !document.formname.fieldname[1].checked && !document.formname.fieldname[2].checked && !document.formname.fieldname[3].checked) { alert("Please choose a group designation.\n"); return false; }

Check if textbox has any characters in it. if (document.formname.fieldname.value.length == 0) { alert("Please fill out your name.\n"); return false; }

Check if multiple checkboxes have not been selected.Replace false with true to see if all are selected. if (document.formname.fieldname.checked == false && document.formname.fieldname.checked == false && document.formname.fieldname.checked == false) { alert("Please select at least one checkbox.\n"); return false; }

Check drop down has been selected. Set drop down's value to Not_Selected for this to work. if (document.formname.fieldname.value == 'Not_Selected') { alert("Please provide us with a selection.\n"); return false; }

Scan values in a field and if they are all letters then alert. The second block of code does the same but for numbers //alert on finding all letters var noalpha = /^[a-zA-Z]*$/; if (noalpha.test(document.formname.fieldname.value)) { alert("Please enter at least one number in the \"username\" field."); return false; } //alert on finding all numbers var nonums = /^[0-9]*$/; if (nonums.test(document.formname.fieldname.value)) { alert("Please enter at least one letter in the \"username\" field."); return false; }

Remove special characters from a string. function clearText() { document.formname.fieldname.value=filterNum(document.formname.fieldname.value) function filterNum(str) { re = /\$|,|@|#|~|`|\%|\*|\^|\&|\(|\)|\+|\=|\[|\-|\_|\]|\[|\}|\{|\;|\:|\'|\"|\<|\>|\?|\||\\|\!|\$|\./g; // remove special characters like "$" and "," etc... return str.replace(re, ""); } }

Detect special characters in text box. Or any character you subsitute for the special characters. var iChars = "!@#$%^&*()+=-[]\\\';,./{}|\":<>?"; for (var i = 0; i < document.formname.fieldname.value.length; i++) { if (iChars.indexOf(document.formname.fieldname.value.charAt(i)) != -1) { alert ("The box has special characters. \nThese are not allowed.\n"); return false; } }