Question

I want to do something kind of Rubyish in Javascript. I’m writing a wrapper around setting DOM element styles. That would go something like (on a per style basis):

ele.style.backgroundColor = someSetting
ele.style.padding = anotherSetting

What I’d like to do (and I’ll use Ruby syntax to illustrate) is:

class Element
  def initialize(ele)
    @ele = ele
  end

  def setDOMElementStyle(styleSettings = {})
    styleSettings.each_pair do |styleAttribute, setting|
      @element.style.send(styleAttribute, setting)
  end

  # Other wrapper stuff for elements here
end

element = Element.new document.createElement("div")
element.setDOMElementStyle :width => '60px', :height => '2px', :top => '0px', :left => '0px'

In Javascript, I can do this with the dreaded eval, but I wondered if there was a neater way to handle it. Here’s a hack at it with the evil eval.

var Element, element;

Element = function() {
  function Element(element) {
    this.element = element;
  }
  Element.prototype.setDOMElementStyle = function(styleSettings) {
    var setting, styleAttribute;

    if (styleSettings == null) {
      styleSettings = {};
    }
    for (setting in styleSettings) {
      styleAttribute = styleSettings[setting];
      eval("@element.style." + styleAttribute + " = " + setting);
    }
  }
}

element = new Element(document.createElement("div"));
element.setDOMElementStyle({
  width: '60px',
  height: '2px',
  top: '0px',
  left: '0px'
});

Thanks!

Answer 1

Use square braces:

element.style[styleAttribute] = setting

In JavaScript, every property can also be referred through square braces. Examples:

window.location.href === window["location"].href === window["location"]["href"]
    === window.location["href"]