Autosizing textarea using Prototype

Question

I'm currently working on an internal sales application for the company I work for, and I've got a form that allows the user to change the delivery address.

Now I think it would look much nicer, if the textarea I'm using for the main address details would just take up the area of the text in it, and automatically resize if the text was changed.

Here's a screenshot of it currently.

Any ideas?

---

@Chris

A good point, but there are reasons I want it to resize. I want the area it takes up to be the area of the information contained in it. As you can see in the screen shot, if I have a fixed textarea, it takes up a fair wack of vertical space.

I can reduce the font, but I need address to be large and readable. Now I can reduce the size of the text area, but then I have problems with people who have an address line that takes 3 or 4 (one takes 5) lines. Needing to have the user use a scrollbar is a major no-no.

I guess I should be a bit more specific. I'm after vertical resizing, and the width doesn't matter as much. The only problem that happens with that, is the ISO number (the large "1") gets pushed under the address when the window width is too small (as you can see on the screenshot).

It's not about having a gimick; it's about having a text field the user can edit that won't take up unnecessary space, but will show all the text in it.

Though if someone comes up with another way to approach the problem I'm open to that too.

---

I've modified the code a little because it was acting a little odd. I changed it to activate on keyup, because it wouldn't take into consideration the character that was just typed.

resizeIt = function() {
  var str = $('iso_address').value;
  var cols = $('iso_address').cols;
  var linecount = 0;

  $A(str.split("\n")).each(function(l) {
    linecount += 1 + Math.floor(l.length / cols); // Take into account long lines
  })

  $('iso_address').rows = linecount;
};

Answer 1

My solution not using jQuery (because sometimes they don't have to be the same thing) is below. Though it was only tested in Internet Explorer 7, so the community can point out all the reasons this is wrong:

textarea.onkeyup = function () { this.style.height = this.scrollHeight + 'px'; }

So far I really like how it's working, and I don't care about other browsers, so I'll probably apply it to all my textareas:

// Make all textareas auto-resize vertically
var textareas = document.getElementsByTagName('textarea');

for (i = 0; i<textareas.length; i++)
{
    // Retain textarea's starting height as its minimum height
    textareas[i].minHeight = textareas[i].offsetHeight;

    textareas[i].onkeyup = function () {
        this.style.height = Math.max(this.scrollHeight, this.minHeight) + 'px';
    }
    textareas[i].onkeyup(); // Trigger once to set initial height
}

Answer 2

Here is a solution with JQuery:

$(document).ready(function() {
    var $abc = $("#abc");
    $abc.css("height", $abc.attr("scrollHeight"));
})

abc is a teaxtarea.

Answer 3

Here is an extension to the Prototype widget that Jeremy posted on June 4th:

It stops the user from entering more characters if you're using limits in textareas. It checks if there are characters left. If the user copies text into the textarea, the text is cut off at the max. length:

/**
 * Prototype Widget: Textarea
 * Automatically resizes a textarea and displays the number of remaining chars
 * 
 * From: http://stackoverflow.com/questions/7477/autosizing-textarea
 * Inspired by: http://github.com/jaz303/jquery-grab-bag/blob/63d7e445b09698272b2923cb081878fd145b5e3d/javascripts/jquery.autogrow-textarea.js
 */
if (window.Widget == undefined) window.Widget = {}; 

Widget.Textarea = Class.create({
  initialize: function(textarea, options){
    this.textarea = $(textarea);
    this.options = $H({
      'min_height' : 30,
      'max_length' : 400
    }).update(options);

    this.textarea.observe('keyup', this.refresh.bind(this));

    this._shadow = new Element('div').setStyle({
      lineHeight : this.textarea.getStyle('lineHeight'),
      fontSize : this.textarea.getStyle('fontSize'),
      fontFamily : this.textarea.getStyle('fontFamily'),
      position : 'absolute',
      top: '-10000px',
      left: '-10000px',
      width: this.textarea.getWidth() + 'px'
    });
    this.textarea.insert({ after: this._shadow });

    this._remainingCharacters = new Element('p').addClassName('remainingCharacters');
    this.textarea.insert({after: this._remainingCharacters});  
    this.refresh();  
  },

  refresh: function(){ 
    this._shadow.update($F(this.textarea).replace(/\n/g, '<br/>'));
    this.textarea.setStyle({
      height: Math.max(parseInt(this._shadow.getHeight()) + parseInt(this.textarea.getStyle('lineHeight').replace('px', '')), this.options.get('min_height')) + 'px'
    });

    // Keep the text/character count inside the limits:
    if($F(this.textarea).length > this.options.get('max_length')){
      text = $F(this.textarea).substring(0, this.options.get('max_length'));
        this.textarea.value = text;
        return false;
    }

    var remaining = this.options.get('max_length') - $F(this.textarea).length;
    this._remainingCharacters.update(Math.abs(remaining)  + ' characters remaining'));
  }
});

Answer 4

Check the below link: http://james.padolsey.com/javascript/jquery-plugin-autoresize/

$(document).ready(function () {
    $('.ExpandableTextCSS').autoResize({
        // On resize:
        onResize: function () {
            $(this).css({ opacity: 0.8 });
        },
        // After resize:
        animateCallback: function () {
            $(this).css({ opacity: 1 });
        },
        // Quite slow animation:
        animateDuration: 300,
        // More extra space:
        extraSpace:20,
        //Textarea height limit
        limit:10
    });
});

Answer 5

Just revisiting this, I've made it a little bit tidier (though someone who is full bottle on Prototype/JavaScript could suggest improvements?).

var TextAreaResize = Class.create();
TextAreaResize.prototype = {
  initialize: function(element, options) {
    element = $(element);
    this.element = element;

    this.options = Object.extend(
      {},
      options || {});

    Event.observe(this.element, 'keyup',
      this.onKeyUp.bindAsEventListener(this));
    this.onKeyUp();
  },

  onKeyUp: function() {
    // We need this variable because "this" changes in the scope of the
    // function below.
    var cols = this.element.cols;

    var linecount = 0;
    $A(this.element.value.split("\n")).each(function(l) {
      // We take long lines into account via the cols divide.
      linecount += 1 + Math.floor(l.length / cols);
    })

    this.element.rows = linecount;
  }
}

Just it call with:

new TextAreaResize('textarea_id_name_here');

Answer 6

Here is a function I just wrote in jQuery to do it - you can port it to Prototype, but they don't support the "liveness" of jQuery so elements added by Ajax requests will not respond.

This version not only expands, but it also contracts when delete or backspace is pressed.

This version relies on jQuery 1.4.2.

Enjoy ;)

http://pastebin.com/SUKeBtnx

Usage:

$("#sometextarea").textareacontrol();

or (any jQuery selector for example)

$("textarea").textareacontrol();

It was tested on Internet Explorer 7/Internet Explorer 8, Firefox 3.5, and Chrome. All works fine.