Several methods to remove spaces on the left and right sides of strings in js_javascript skills

//recon idea:
//-------------
//Remove the space on the left side of the string
function ltrim(str)
{
if (str.charat(0) == " ")
{
//If the first character on the left side of the string is a space
str = str.slice(1);//Remove the space from the character Remove
from the string //This sentence can also be changed to str = str.substring(1, str.length);
str = ltrim(str); //Recursive call
}
return str ;
}

//Remove the spaces on the right side of the string
function rtrim(str)
{
var ilength;

ilength = str.length;
if (str.charat(ilength - 1) == " ")
{
//If the first character on the right side of the string is a space
str = str.slice(0, ilength - 1 );//Remove spaces from the string
//This sentence can also be changed to str = str.substring(0, ilength - 1);
str = rtrim(str); //Recursive call
}
return str;
}

//Remove spaces on both sides of the string
function trim(str)
{
return ltrim(rtrim(str)) ;
}

//Rainy Day 5337’s idea:
//----------------
function alltrim(a_strvarcontent)
{
var pos1, pos2, newstring;

pos1 = 0;
pos2 = 0;
newstring = ""

if (a_strvarcontent.length > 0)
{
for( i=0; i //recon: This sentence should be wrong and should be changed to:
//for( i=0; i {
if (a_strvarcontent.charat(i) == " " )
pos1 = pos1 1;
else
break;
}

for( i=a_strvarcontent.length; i>=0 ; i--)
//recon: This sentence should be wrong and should be changed to:
//for( i=a_strvarcontent.length -1; i>=0 ; i--)
{
if ( a_strvarcontent.charat(i) == " " )
pos2 = pos2 1;
else
break;
}

newstring = a_strvarcontent.substring(pos1, a_strvarcontent.length-pos2)

}

return newstring;

}

//hooke’s idea:
//-------------
function jtrim(sstr)
{
var astr="";
var dstr="";
var flag=0;
for (i=0;i {if ((sstr.charat(i)!=' ')| |(flag!=0))
{dstr =sstr.charat(i);
flag=1;
}
}
flag=0;
for (i= dstr.length-1;i>=0;i--)
{if ((dstr.charat(i)!=' ')||(flag!=0))
{astr =dstr. charat(i);
flag=1;
}
}
dstr="";
for (i=astr.length-1;i>=0;i--) dstr =astr.charat(i);
return dstr;
}
Why not use regular expressions?
String.prototype.Trim = function()
{
return this.replace(/(^s*)|(s*$)/g, "");
}