JavaScript之PadLeft,PadRight

String.prototype.PadLeft = function(totalWidth, paddingChar)

{

if ( paddingChar != null )

{

return this.PadHelper(totalWidth, paddingChar, false);

} else {

return this.PadHelper(totalWidth, ' ', false);

}

}

String.prototype.PadRight = function(totalWidth, paddingChar)

{

if ( paddingChar != null )

{

return this.PadHelper(totalWidth, paddingChar, true);

} else {

return this.PadHelper(totalWidth, ' ', true);

}

}

String.prototype.PadHelper = function(totalWidth, paddingChar, isRightPadded)

{

if ( this.length < totalWidth)

{

var paddingString = new String();

for (i = 1; i <= (totalWidth - this.length); i++)

{

paddingString += paddingChar;

}

if ( isRightPadded )

{

return (this + paddingString);

} else {

return (paddingString + this);

}

} else {

return this;

}

}