substr in javascript

Syntax

string.substr(start,length)

Parameter	Description
start	Required. The index where to start the extraction. First character is at index 0
length	Optional. The number of characters to extract. If omitted, it extracts the rest of the string

Example

Example

Extract characters from a string:

The output of the code above will be:

v
vR

how to get xmldoc in a string

put this line wherever u needed to do this.


var string = (new XMLSerializer()).serializeToString(xmlDoc);

how to load a string into dom

//------------- load a string into dom --------
//@param: string to be loaded
//@return: xml dom document
function dom_load(string)
{
//alert("dom_load");
if (window.DOMParser)
  {
  parser=new DOMParser();
  xmlDoc=parser.parseFromString(string,"text/xml");
  }
  else // Internet Explorer
  {
  xmlDoc=new ActiveXObject("Microsoft.XMLDOM");
  xmlDoc.async="false";
  xmlDoc.loadXML(string);
 
  }
}

angle between two points in javascript

//--------- to get angle between two points ---------
//---param---
//@x1,x2,y1,y2 : cordinates of 2 points
//@return: theta(value in degrees)
function getTanTheta(x1,y1,x2,y2)
{
var y = eval(y2)-eval(y1);
var x = eval(x2)-eval(x1);

if(y < 0) { y = -y;}
if(x < 0) { x = -x;}

//alert(y+'  '+x);
var tanTheta = y/x;
if(tanTheta < 0) { tanTheta = -x;}

tanTheta = roundNumber(tanTheta,3);
//alert(tanTheta);
return tanTheta;

}

Round number in javascript

//------- Rounding in javascript --------
//@param: Number, length to round
//@return: Rounded number

function roundNumber(rnum, rlength) 

{
// Arguments: number to round, number of decimal places
  var newnumber = Math.round(rnum*Math.pow(10,rlength))/Math.pow(10,rlength);
    newNumber = parseFloat(newnumber); // Output the result to the form field (change for your purposes)
    return newNumber;
}