Set maxlength in Html Textarea [duplicate]

2019-01-06 12:41发布

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How can I set the maxlength in a textarea? And why maxlength is not working properly in textarea?

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【Aperson】
2楼-- · 2019-01-06 13:13

resize:none; This property fix your text area and bound it. you use this css property id your textarea.gave text area an id and on the behalf of that id you can use this css property.

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可以哭但决不认输i
3楼-- · 2019-01-06 13:16 
<p>
   <textarea id="msgc" onkeyup="cnt(event)" rows="1" cols="1"></textarea> 
</p> 
<p id="valmess2" style="color:red" ></p>

function cnt(event)
{ 
 document.getElementById("valmess2").innerHTML=""; // init and clear if b < max     
allowed character 

 a = document.getElementById("msgc").value; 
 b = a.length; 
 if (b > 400)
  { 
   document.getElementById("valmess2").innerHTML="the max length of 400 characters is 
reached, you typed in  " + b + "characters"; 
  } 
}

maxlength is only valid for HTML5. For HTML/XHTML you have to use JavaScript and/or PHP. With PHP you can use strlen for example.This example indicates only the max length, it's NOT blocking the input.

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混吃等死
4楼-- · 2019-01-06 13:20

Before HTML5, we have an easy but workable way: Firstly set an maxlength attribute in the textarea element:

<textarea maxlength='250' name=''></textarea>

Then use JavaScript to limit user input:

$(function() {  
    $("textarea[maxlength]").bind('input propertychange', function() {  
        var maxLength = $(this).attr('maxlength');  
        if ($(this).val().length > maxLength) {  
            $(this).val($(this).val().substring(0, maxLength));  
        }  
    })  
});

Make sure the bind both "input" and "propertychange" events to make it work on various browsers such as Firefox/Safari and IE.

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\"骚年 ilove
5楼-- · 2019-01-06 13:20

If you are using HTML 5, you need to specify that in your DOCTYPE declaration.

For a valid HTML 5 document, it should start with:

<!DOCTYPE html>

Before HTML 5, the textarea element did not have a maxlength attribute.

You can see this in the DTD/spec:

<!ELEMENT TEXTAREA - - (#PCDATA)       -- multi-line text field -->
<!ATTLIST TEXTAREA
  %attrs;                              -- %coreattrs, %i18n, %events --
  name        CDATA          #IMPLIED
  rows        NUMBER         #REQUIRED
  cols        NUMBER         #REQUIRED
  disabled    (disabled)     #IMPLIED  -- unavailable in this context --
  readonly    (readonly)     #IMPLIED
  tabindex    NUMBER         #IMPLIED  -- position in tabbing order --
  accesskey   %Character;    #IMPLIED  -- accessibility key character --
  onfocus     %Script;       #IMPLIED  -- the element got the focus --
  onblur      %Script;       #IMPLIED  -- the element lost the focus --
  onselect    %Script;       #IMPLIED  -- some text was selected --
  onchange    %Script;       #IMPLIED  -- the element value was changed --
  %reserved;                           -- reserved for possible future use --
  >

In order to limit the number of characters typed into a textarea, you will need to use javascript with the onChange event. You can then count the number of characters and disallow further typing.

Here is an in-depth discussion on text input and how to use server and client side scripting to limit the size.

Here is another sample.

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成全新的幸福
6楼-- · 2019-01-06 13:22

Before HTML5 it's only possible to check this with JavaScript or by a server-side verification (better, because JavaScript obviously only works with JavaScript enabled...). There is no native max-length attribute for textareas.

Since HTML5 it's a valid attribut, so defining your doctype as HTML5 may help. I don't know if all browsers support this attribute, though:

<!DOCTYPE html>
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成全新的幸福
7楼-- · 2019-01-06 13:29 
$(function(){  
  $("#id").keypress(function() {  
    var maxlen = 100;
    if ($(this).val().length > maxlen) {  
      return false;
    }  
  })
});
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