SVG:Script

preventing default behaviour in event code

when writing drag and drop code, you will realize that text on the page gets accidently selected while dragging. or if you want to use the backspace key in your code, you want to prevent the browser from going back to the last page. in these cases, one can use the evt.preventDefault() method.

using eventListeners with objects

the methods addEventListener()and removeEventListener() are very usefull when writing interactive SVG. you can pass an object as the second parameter to that methods. this object has to implement the handleEvent interface.

function myRect(x,y,w,h,message){
 this.message=message

 this.rect=document.createElementNS("http://www.w3.org/2000/svg","rect")
 this.rect.setAttribute("x",x)
 this.rect.setAttribute("y",y)
 this.rect.setAttribute("width",w)
 this.rect.setAttribute("height",h)
 document.documentElement.appendChild(this.rect)

 this.rect.addEventListener("click",this,false)

 this.handleEvent= function(evt){
   switch (evt.type){
    case "click":
     alert(this.message)
     break;
    }
   }
  }

inter-document scripting

When calling a JavaScript function that resides in the HTML file, from an SVG file that is embedded in an HTML document, one should use 'parent.functionname();' to reference such a function. The Adobe SVG viewer plugin allows the use of functionname(), but 'parent.functionname()' also works, so in this case using 'parent.functionname()' is preferred.

Update: according to the SVG-Whiz wiki the "parent" JS variable is broken in Adobe's SVG version 6 preview plugin. The suggested workaround is to use "top" instead of "parent". Since it is a Beta version of their plugin, we can probably safely ignore this.

setProperty has three parameters

The function svgElement.style.setProperty("fill-opacity", "0.0") throws a DOMException - SYNTAX ERR in Mozilla. This behaviour is specified by the W3C in the DOM Level 2 Style Specification. The function setProperty is defined as a function with three parameters. The above can be replaced with 'svgElement.style.setProperty("fill-opacity", "0.0", "")', which is standards compliant.

Links

SVG:Home Page

SVG-Whiz wiki on Scripting and Programming