JavaScript text box verification code based on regular expression

Time:2021-5-2

1, cannot be empty
<input   Type = “text” onblur = “if (this. Value. Replace (/ ^ + | + $/ g, ‘) =’) alert (‘cannot be empty ‘)” > “

2. Only English and numbers can be input
< input onblur = “if (/ [^ 0-9a-zA-Z] / g.test (value)) alert (‘wrong ‘)” >
<input onkeyup=”value=value.replace(/[^0-9a-zA-Z]/g,”)”/>
<input type=”text” onkeyup=”value=value.replace(/[^\a-\z\A-\Z0-9]/g,”)”>

3. Judge that characters are composed of letters and numbers, underscores and dots. And the beginning can only be underscores and letters
/^([a-zA-z_]{1})([\w]*)$/g.test(str)

4, only numbers can be input
<input name=”text” type=”text” onKeyUp=”value=value.replace(/\D/g,”)” onafterpaste=”value=value.replace(/\D/g,”)” >

5, only Chinese can be input
<input type=”text” onkeyup=”value=value.replace(/[^\u4E00-\u9FA5]/g,”)”>

6, English only
<input type=”text” onkeyup=”value=value.replace(/[^\a-\z\A-\Z]/g,”)”>
<input type=”text” onkeyup=”value=value.replace(/[^a-zA-Z]/g,”)”>

7, only Chinese, English, number, @ symbol and. Symbol can be input
<input type=”text” onkeyup=”value=value.replace(/[^\a-\z\A-\Z0-9\u4E00-\u9FA5\@\.]/g,”)”>

8, only English is allowed to be input, and neither paste nor pop-up paste menu is allowed
<input type=”text” onkeyup=”value=value.replace(/[^\a-\z\A-\Z]/g,”)” onkeydown=”fncKeyStop(event)” onpaste=”return false” oncontextmenu = “return false”/>

Only numbers and point numbers can be entered(be careful:D in [^ D \.] cannot be written as capital D, otherwise it will become all characters except numbers)
<input name=”price” type=”text” size=”8″ maxlength=”8″ onkeyup=”value=value.replace(/[^\d\.]/g,”)” >

In a word: first, enter onkeyup = “value = value. Replace (/ [^ x] / g, ‘”) in < input >, and then replace the X in (/ [^ x] / g,’) with the code you want to enter

chinese:u4E00-u9FA5
number:d、0-9
english:a-z、A-Z
Other symbols @, dots or other symbols. You can also have more than one, separated by
For example:
Chinese, English and numbers with @ symbol and dot symbol: a – < br > Z / a – < br > z0-9 / u4e00 – < br > u9fa5 \ @ \

If you don’t want to pop up the menu and paste the copied information in the text box, you need to enter onkeydown = “fnckeystop (event)” onpaste = “return false” oncontextmenu = “return false;” in < input >

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