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This pointer JavaScript reference (complex)

Experts,

I am making a generic trim function for JavaScript and extending this trim function the String object in JavaScript.

I have two functions that do the trim. rtrim and ltrim. As the names imply they trim the right and left sides of the string. However, since I am extending this function to the JavaScript String object I am using the this pointer to pass information between the two functions. But, it does not appear to work.

--Code Begin---
String.prototype.trim=function()
{
var trimedStr = this.rtrim(this.ltrim());
return trimedStr;
}

String.prototype.ltrim=function()
{
var trimChars = new Array(9,10,13,32);
var trimStrLen = this.length;
var startidx = 0;
var trimedStr = "";

for (var i=0;i<trimStrLen;i++)
{
if (this.charCodeAt(i) != trimChars[0] && this.charCodeAt(i) != trimChars[1] &&
this.charCodeAt(i) != trimChars[2] && this.charCodeAt(i) != trimChars[3])
{
startidx = i;
break;
}
}

return this.substring(startidx,trimStrLen);
}

String.prototype.rtrim=function()
{
var trimChars = new Array(9,10,13,32);
var trimStrLen = this.length-1;
var startidx = trimStrLen;
var trimedStr = "";

for (var i=trimStrLen;i>0;i--)
{
if (this.charCodeAt(i) != trimChars[0] && this.charCodeAt(i) != trimChars[1] &&
this.charCodeAt(i) != trimChars[2] && this.charCodeAt(i) != trimChars[3])
{
startidx = i;
break;
}
}

return this.substring(0,startidx+1);
}

var mytestvar = " -teststring- ";
var trimstr;

alert(mytestvar.length);
trimstr = mytestvar.trim();
alert(trimstr.length);
--Code End--

If I change the (trimstr = mytestvar.trim();) to (trimstr = mytestvar.rtrim(); or trimstr = mytestvar.ltrim();) then the string comes back trimed. But, not when I use the main function that is supposed to call both routines.

Any ideas?
-mmetzger

mmetzger

ASKER

Solution was found on my own.

<b>Please refund my points EE.</b>

Solution as follows: posted by mmetzger

function trim(trimStr)
{
var trimedStr = rtrim(ltrim(trimStr));
return trimedStr;
}

function ltrim(trimStr)
{
var trimStrLen = trimStr.length;

for (var i=0;i<trimStrLen;i++)
{
var aCharCode = trimStr.charCodeAt(i);

if (isWhiteSpace(aCharCode) == false)
{
break;
}
}

return trimStr.substring(i,trimStrLen);
}

function rtrim(trimStr)
{
var trimStrLen = trimStr.length-1;

for (var i=trimStrLen;i>0;i--)
{
var aCharCode = trimStr.charCodeAt(i);

if (isWhiteSpace(aCharCode) == false)
{
break;
}
}

return trimStr.substring(0,i+1);
}

function isWhiteSpace(possWsChar)
{
/* White space chars
9 = TAB
10 = LF (line feed)
12 = FF (form feed)
13 = CR (Carriage return)
32 = Space */

var trimChars = new Array(9,10,12,13,32);
var WsFound = false;

for (var i=0;i<trimChars.length;i++)
{
if (possWsChar == trimChars[i])
{
WsFound = true;
}
}

return WsFound;
}

jaysolomon

No comment has been added lately, so it's time to clean up this TA.
I will leave the following recommendation for this question in the Cleanup topic area:

PAQ with points refunded

Please leave any comments here within the next four days.
PLEASE DO NOT ACCEPT THIS COMMENT AS AN ANSWER!

jAy
EE Cleanup Volunteer

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