JavaScript-the second of regular expression

The approximate matching process for regular expressions is to take out the expression and compare the characters in the text, and if each character matches, the match succeeds; If a match is unsuccessful, the match fails.

Regular expressions are typically used to find matching strings in text. The number of words in Python is greedy by default (which may be the default non-greedy in a few languages), always trying to match as many characters as possible, and not greedy, instead, always trying to match as few characters as possible. For example: the regular expression "ab*" will find "abbb" if it is used to find "ABBBC". And if you use a non-greedy quantity word "ab*?", you will find "a".

1. Length Limit
<script>
function test ()
{
if (DOCUMENT.A.B.VALUE.LENGTH>50)
{
Alert ("Cannot exceed 50 characters!") ");
Document.a.b.focus ();
return false;
}
}
</script>
<form name=a onsubmit= "return Test ()" >
<textarea name= "B" cols= "+" wrap= "VIRTUAL" rows= "6" ></textarea>
<input type= "Submit" name= "Submit" value= "Check" >
</form>

2. Can only be Chinese characters
<input onkeyup= "value="/oblog/value.replace (/[^\u4e00-\u9fa5]/g, ') ">

3. "Can only be in English
<script language=javascript>
function Onlyeng ()
{
if (! ( EVENT.KEYCODE>=65&&EVENT.KEYCODE<=90))
Event.returnvalue=false;
}
</script>

<input onkeydown= "Onlyeng (); >

4. Can only be a number
<script language=javascript>
function Onlynum ()
{
if (! ( (event.keycode>=48&&event.keycode<=57) | | (event.keycode>=96&&event.keycode<=105)))
Consider the numeric keys on the keypad
Event.returnvalue=false;
}
</script>

<input onkeydown= "Onlynum (); >

5. Only English characters and numbers
<input onkeyup= "value="/oblog/value.replace (/[\w]/g, "')" onbeforepaste= "Clipboarddata.setdata (' text ', Clipboarddata.getdata (' text '). Replace (/[^\d]/g, ')) ">

6. Verify the fuel tank format
<script Language=javascript runat=server>
function Isemail (stremail) {
if (Stremail.search (/^\w+ (-\w+) | ( \.\w+)) *\@[a-za-z0-9]+ ((\.| -) [a-za-z0-9]+] *\. [a-za-z0-9]+$/)! =-1)
return true;
Else
Alert ("Oh");
}
</SCRIPT>
<input type=text onblur=isemail (this.value) >

7. Block Keywords (shield * * * and * * * * here)
<script language= "javascript1.2" >
function Test () {
if ((A.b.value.indexof ("* * *") = = 0) | | (A.b.value.indexof ("* * *") = = 0)) {
Alert ("");
A.b.focus ();
return false;}
}
</script>
<form name=a onsubmit= "return Test ()" >
<input Type=text name=b>
<input type= "Submit" name= "Submit" value= "Check" >
</form>

8. Two times the same password is entered
<form method=post action= "" >
<input type= "Password" id= "INPUT1" >
<input type= "Password" id= "Input2" >
<input type= "button" value= "Test" onclick= "Check ()" >
</FORM>
<script>
function Check ()
{
With (document.all) {
if (Input1.value!=input2.value)
{
Alert ("false")
Input1.value = "";
Input2.value = "";
}
else Document.forms[0].submit ();
}
}
</script>
That's enough.
Shield Right button is cool
Oncontextmenu= "return false" ondragstart= "return false" onselectstart= "return False"
Add it to the body.

Two

2.1 The form item cannot be empty

<script language= "JavaScript" >
<!--
function Checkform ()
{
if (Document.form.name.value.length = = 0) {
Alert ("Please enter your name!");
Document.form.name.focus ();
return false;
}
return true;
}
-
</script>

2.2 Compare two table items for the same value

<script language= "JavaScript" >
<!--
function Checkform ()
if (document.form.PWD.value! = document.form.PWD_Again.value) {
Alert ("The password you entered two times is different!") Please re-enter. ");
Document. ADDUser.PWD.focus ();
return false;
}
return true;
}
-
</script>

2.3 Form items can only be numeric and "_" for phone/bank account verification, can be extended to domain name registration, etc.

<script language= "JavaScript" >
<!--
function Isnumber (String)
{
var Letters = "1234567890-"; can increase the input value by itself
var i;
var C;
if (String.charat (0) = = '-')
return false;
if (String.charat (string.length-1) = = '-')
return false;
for (i = 0; i < string.length; i + +)
{
c = String.charat (i);
if (Letters.indexof (c) < 0)
return false;
}
return true;
}
function Checkform ()
{
if (! Isnumber (Document.form.TEL.value)) {
Alert ("Your phone number is not legal!") ");
Document.form.TEL.focus ();
return false;
}
return true;
}
-
</script>

2.4 Table Item input value/length limit

<script language= "JavaScript" >
<!--
function Checkform ()
{
if (Document.form.count.value > | | Document.form.count.value < 1)
{
Alert ("Input value cannot be less than 0 greater than 100!");
Document.form.count.focus ();
return false;
}
if (document.form.message.value.length<10)
{
Alert ("Input text less than 10!");
Document.form.MESSAGE.focus ();
return false;
}
return true;
}
-
</script>

2.5 Chinese/English/digital/e-mail address legality judgment

<script language= "JavaScript" >
<!--

function Isenglish (name)//English value detection
{
if (Name.length = = 0)
return false;
for (i = 0; i < name.length; i++) {
if (Name.charcodeat (i) > 128)
return false;
}
return true;
}

function Ischinese (name)//Chinese value detection
{
if (Name.length = = 0)
return false;
for (i = 0; i < name.length; i++) {
if (Name.charcodeat (i) > 128)
return true;
}
return false;
}

function IsMail (name)//e-mail value detection
{
if (! Isenglish (name))
return false;
i = Name.indexof ("at");
j = Name Dot LastIndexOf ("at");
if (i = =-1)
return false;
if (i! = j)
return false;
if (i = = Name dot length)
return false;
return true;
}

function Isnumber (name)//numeric detection
{
if (Name.length = = 0)
return false;
for (i = 0; i < name.length; i++) {
if (Name.charat (i) < "0" | | name.charat (i) > "9")
return false;
}
return true;
}

function Checkform ()
{
if (! IsMail (Form). Email.value)) {
Alert ("Your email is illegal!") ");
Form. Email.focus ();
return false;
}
if (! isenglish (Form.name.value)) {
Alert ("English name is not legal!") ");
Form.name.focus ();
return false;
}
if (! Ischinese (Form.cnname.value)) {
Alert ("Chinese name is not legal!") ");
Form.cnname.focus ();
return false;
}
if (! isnumber (Form). Publiczipcode.value)) {
Alert ("ZIP code is illegal! ");
Form. Publiczipcode.focus ();
return false;
}
return true;
}
-
</SCRIPT>

2.6 Characters that limit the entry of a form item

<script language= "JavaScript" >
<!--

function contain (Str,charset)//string contains test function
{
var i;
for (i=0;i<charset.length;i++)
if (Str.indexof (Charset.charat (i)) >=0)
return true;
return false;
}

function Checkform ()
{
if (Contain (Document.form.NAME.value, "%\ (\) ><")) | | (Contain (Document.form.MESSAGE.value, "%\ (\) ><")))
{
Alert ("illegal character entered");
Document.form.NAME.focus ();
return false;
}
return true;
}
-

JavaScript-the second of regular expression