Altering input field width This gets every form element and calculates its width, then changes the input fields depending on the parent-form width:

$ -&gt;
 # Alter 'input' Width
  inputResize = -&gt; 
   $('form').each -&gt;
    tF = $(this)
    formWidth = tF.width()
    tF.find('input').each -&gt;
     tE = $(this)
     inputBorder = (tE.outerWidth() - tE.innerWidth())
     inputPadding = parseInt(tE.css('padding-left')) + parseInt(tE.css('padding-right'))
     tE.css 'width', -&gt;
      (formWidth - inputBorder - inputPadding)
 # on Resize
 $(window).resize -&gt;
  inputResize()
 # on Init
  inputResize()


It works as intended, but to learn a bit more I just want to know if there is a smarter way to write this little code in CoffeeScript.
Here are a few tips:
1) Use standard naming convention.
tE and tF sound like booleans and not a refence to an element.
Try names like el, $this or that instead.
2) Separate complex logic into smaller functions.
There's too much going on here.
 inputResize = -&gt; 
   $('form').each -&gt;
    tF = $(this)
    formWidth = tF.width()
    tF.find('input').each -&gt;
     tE = $(this)
     inputBorder = (tE.outerWidth() - tE.innerWidth())
     inputPadding = parseInt(tE.css('padding-left')) + parseInt(tE.css('padding-right'))
     tE.css 'width', -&gt;
      (formWidth - inputBorder - inputPadding)
      

Since tF is only used then you can get rid of it and use $(this) directly.
Next, extract the input width size calculation to one function and you get something like this.
  getNewInputSize = (el, formWidth) -&gt;
    inputBorder = el.outerWidth() - el.innerWidth()
    inputPadding = parseInt( el.css(&quot;padding-left&quot;), 10) + parseInt(el.css(&quot;padding-right&quot;), 10)
    formWidth - inputBorder - inputPadding

  resizeFormInputs = -&gt;
    $(&quot;form&quot;).each -&gt;
      formWidth = $(this).width()
      $(this).find(&quot;input&quot;).each -&gt;
        $(this).css &quot;width&quot;, getNewInputSize($(this), formWidth)

Final Code:
$ -&gt;
  getNewInputSize = (el, formWidth) -&gt;
    inputBorder = el.outerWidth() - el.innerWidth()
    inputPadding = parseInt( el.css(&quot;padding-left&quot;), 10) + parseInt(el.css(&quot;padding-right&quot;), 10)
    formWidth - inputBorder - inputPadding

  resizeFormInputs = -&gt;
    $(&quot;form&quot;).each -&gt;
      formWidth = $(this).width()
      $(this).find(&quot;input&quot;).each -&gt;
        $(this).css &quot;width&quot;, getNewInputSize($(this), formWidth)
        
  $(window).resize(resizeFormInputs).triggerHandler &quot;resize&quot;