How to limit the textarea to only hold numbers?

2019-02-23 09:26发布

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问题:

I'm trying to make a date textbox on my blog, and the date is only numbers. I don't want anybody making a mistake typing a letter. Is there any way to limit the characters to only numerals? Thanks!

回答1:

If you use jQuery, you can do it like in this jsfiddle

$('input').keypress(function(e) {
    var a = [];
    var k = e.which;

    for (i = 48; i < 58; i++)
        a.push(i);

    if (!(a.indexOf(k)>=0))
        e.preventDefault();
});


回答2:

Use HTML5 input number type instead and leverage native browser validation. Thus, no JavaScript required.

<input type="number" />

It has wide support in browsers and it's the standard and best-practice solution.

Also on mobile and tablets the numeric key pad will appear instead.

See demo



回答3:

you need some java script to implement this

<html>
<head>
<title>Test</title>
<script language="javascript">
function checkInput(ob) {
  var invalidChars = /[^0-9]/gi
  if(invalidChars.test(ob.value)) {
            ob.value = ob.value.replace(invalidChars,"");
      }
}
</script>
</head>

<body>
    <input type="text" onkeyup="checkInput(this)"/>
</body>
</html>


回答4:

Try this (utilizing jquery javascript library)

html

<input type="text" size="30" />

js (jquery library)

$(document).ready(function() {
    $("input").attr("placeholder", "Please input numbers").change(function(e) {
      var txt = /[a-z]/gi.test($(this).val());
      if (txt) {
        $(this).val("").attr("placeholder", "Not a number, please input numbers")
      };
    });
})

jsfiddle http://jsfiddle.net/guest271314/v2BRY/

Edit. Not certain if element is input ot textarea, hope should work for either.

javascript, without utilizing jquery javascript library

html

<input type="text" size="30" />

javascript

function checkText() {   
  var textarea = document.querySelectorAll("input");
  textarea[0].setAttribute("placeholder", "Please input numbers");    
  textarea[0].addEventListener("change", function(e) {
    var txt = /[a-z]/gi.test(e.target.value);
    if (txt) {
      e.target.value = "";
      e.target.setAttribute("placeholder", "Not a number, please input numbers");
    };    
  }, false);
};
checkText()

jsfiddle http://jsfiddle.net/guest271314/pFu4K/

Hope this helps



回答5:

Yes, you need some JavaScript to do this. I found the JQuery date picker widget very useful to do exactly what you're wanting. The code that used to implement it is:

html to create the text field and not allow manual manipulation:

<input type="text" class="header_input" id="tvpostingdate" placeholder="Posting Date" default='' readonly="readonly">

the JS line binding the picker to the field with a specific format that my server side process is expecting:

$('#tvpostingdate').datepicker({ dateFormat: "mmddyy"});

You can find more information here: http://jqueryui.com/datepicker/



标签： html numbers textarea limit
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