Resize TextArea on load

问题

I'm having issues trying to resize a text area, I can do it as the user is typing but when they have submit it this gets put into a database and put into a text area below and display as a message on a message board but if the message exceeds the size of the Text Area it's not displayed I was wondering if anyone out there has had this issue and overcome it.

Here is the solution I came up with for the resizing whilst typing,

function resizeTextarea (id) {
  var a = document.getElementById(id);
  a.style.height = 'auto';
  a.style.height = a.scrollHeight+'px';
}

function init() 
{
  var a = document.getElementsByTagName('textarea');
  for(var i=0,inb=a.length;i<inb;i++) 
  {
     if(a[i].getAttribute('data-resizable')=='true')
     {
      resizeTextarea(a[i].id);
     }
  }
}

addEventListener('DOMContentLoaded', init);

This is called on keyup on the textarea in my other page where ive used it but I have tried to do something like this to resize when it loads but it doesn't work but it does work when a key is pressed or a button is clicked.

onload="resizeTextarea('commentstext');"

I know i could always have it scrollable or put it into a div but divs don't format the text like a textarea if i do a line break in the text and submit it to a div ti wont be there

回答1:

See my modification of prior solution: http://jsfiddle.net/CbqFv/570/

HTML

<textarea cols="42" rows="1">
1 ...by default, you can write more rows</textarea><br />
<br />
<textarea cols="42" rows="5">
1
2
3
4
5 ...by default, you can write more rows</textarea><br />
<br />
<textarea cols="42" rows="10">
1
2
3
4
5
6
7
8
9
10 ...by default, you can write more rows</textarea>

CSS

textarea {
  border: 1px solid gray;
  border-radius: 3px;
  line-height: 1.3em;
  overflow: hidden;
  padding: 0.3em 0.3em 0 0.3em;
  outline: none;
  background-color: white;
  resize: none;
}

JavaScript

var observe;
if (window.attachEvent) {
  observe = function (element, event, handler) {
    element.attachEvent('on'+event, handler);
  };
}
else {
  observe = function (element, event, handler) {
    element.addEventListener(event, handler, false);
  };
}
function init () {
  function resize (element) {
    element.style.height = 'auto';
    element.style.height = element.scrollHeight+'px';
  }
  /* 0-timeout to get the already changed text */
  function delayedResize (element) {
    window.setTimeout(function() { resize(element) }, 0);
  }
  var textareas = document.getElementsByTagName("textarea");
  for (i = 0; i < textareas.length; i++) {
    var textarea = textareas[i];
    observe(textarea, 'change', function() { resize(this) });
    observe(textarea, 'cut', function() { delayedResize(this) });
    observe(textarea, 'paste', function() { delayedResize(this) });
    observe(textarea, 'drop',function() { delayedResize(this) });
    observe(textarea, 'keydown', function() { delayedResize(this) });
    textarea.focus();
    textarea.select();
    resize(textarea);
  }
}

init();

回答2:

from autosize documentation:

Autosize has no way of knowing when the value of a textarea has been changed through JavaScript. If you do this, trigger the autosize.resize event immediately after to update the height. Example:

$('#example').val('New Text!').trigger('autosize.resize');

So after you update the textarea content, you'll have to call that trigger to autoresize it

来源：https://stackoverflow.com/questions/21831181/resize-textarea-on-load

标签

javascript

html

css

textarea