multiline string split problem and fix

[Brian]

I have been working on a data reception system.. I am still finding my
way around Javascript, though I am accomplishing much.

I just fixed a flaw that was really hard to find. The symptoms are
this:

I get a multiline string returned to Javascript from a Proxy+Google
Maps API GDownloadUrl()
The data, when added to a DOM table looked fine, about 20 lines in CSV
format

Sunrise,-119.098,35.345,0.0<br>
SwanDancer,-119.345,35.567,1.0<br>
.... etc

(I don't know why the <br>'s are there, but that's what it looks like)
So using a suggestion from this newsgroup, I perform two subsequent
split()'s

var index, index2;
var strCSVFile = data;
var arrayCSVFile;

arrayCSVFile = strCSVFile.split( "<br>" );

for ( index = 0; index < arrayCSVFile.length; index++ )
{
arrayCSVFile[ index ] = arrayCSVFile[ index ].split( ',' );
// do stuff to the elements
}

I use both strCSVFile *and* arrayCSVFile to be doubly sure I wasn't
somehow clobbering something, though in theory there needs to be only
the original string. At any rate, what I see is this (after HOURS of
trying and finally using str.charCodeAt())

10|32|32|32|32|32|32|32|32|83|117|110|114|105|115|101| len=16
10|10|32|32|32|32|32|32|32|32|83|119|97|110|68|97|110|99|101|114|
len=20
.... etc

%^!@#$^%@ <- that's cursing, people
So I am now hand clipping some number of LF and SPACE chars using
str.charCodeAt(). On top of that, my furtive attempts at RegEx
replacements along the way had been SILENTLY FAILING. Probably because
of the leading LF(s). I had no idea, and it took valuable time..

I looked for split() gotcha's but never found anything like this. I
thought I tried changing the split to "<BR>\r" at one point, but I
probably did the return instead of line feed... Also, that would NOT
handle the first line case ?!

This is what is happening, and I now have tedious code to handle it.
Looking back on the original recv'd data, it does indeed have a leading
LF|SPACE's, with two LF's on every subsequent row. I never saw them.
How could I ? When I aded them to the HTML page to check the data, they
didn't show
This was awful.

FYI

 

[Brian]

btw- I just added

strCSVFile.replace( / /g, '');
strCSVFile.replace( / \n/g, '');
strCSVFile.replace( / \r/g, '');

to clean the data (the whole block before the split()'s. Am I making a
mistake in the RegEx? they don't work...

 

[Brian]

strCSVFile.replace( / /g, '');
strCSVFile.replace( / \n/g, '');
strCSVFile.replace( / \r/g, '');

hmmm, very late night typing.. I meant

strCSVFile.replace( / +/g, '');
strCSVFile.replace( /\n+/g, '');
strCSVFile.replace( /\r+/g, '');

 

[mick white]

hmmm, very late night typing.. I meant

strCSVFile.replace( / +/g, '');
strCSVFile.replace( /\n+/g, '');
strCSVFile.replace( /\r+/g, '');

Perhaps you need:
someVariable=strCSVFile.replace(/\s/g,'');

No need for "+", since you are using the "g" modifier. And why not
assign the result of the statement to a variable? (Unless you want to
destroy the original string.)
Mick

 

[RobG]

I have been working on a data reception system.. I am still finding my
way around Javascript, though I am accomplishing much.

I just fixed a flaw that was really hard to find. The symptoms are
this:

I get a multiline string returned to Javascript from a Proxy+Google
Maps API GDownloadUrl()
The data, when added to a DOM table looked fine, about 20 lines in CSV
format

Sunrise,-119.098,35.345,0.0<br>
SwanDancer,-119.345,35.567,1.0<br>
... etc

Try something like:

var strCSVFile = 'Sunrise,-119.098,35.345,0.0<br>'
+ 'SwanDancer,-119.345,35.567,1.0<br>';

/* Remove any leading or trailing br elements */
strCSVFile = strCSVFile.replace(/(^<br>)|(<br>$)/g,'');

var arrayCSVFile = strCSVFile.split('<br>');
var recordElement;

/* arrayCSVFile is now an array with two elements:
*
* ['Sunrise,-119.098,35.345,0.0',
* 'SwanDancer,-119.345,35.567,1.0']
*/
for (var i=0, len=arrayCSVFile.length; i<len; i++){
arrayCSVFile = arrayCSVFile.split(',');

/* arrayCSVFile is still an array with two elements,
* but each is now an array of 4 elements:
*
* [
* ['Sunrise', '-119.098', '35.345', '0.0'],
* ['SwanDancer', '-119.345', '35.567', '1.0']
* ]
*/
for (var j=0, len2=arrayCSVFile.length; j<len2; j++){
recordElement = arrayCSVFile[j];

/* recordElement will be each element in turn, i.e.
* 'Sunrise', then '-119.098', then '35.345', and so on
*/

alert('Record: ' + (i+1) + ' of ' + len
+ '\nElement: ' + (j+1) + ' of ' + len2
+ '\nValue: ' + recordElement);
}
}

If you want to remove all whitespace (all spaces, tabs, linefeeds,
returns, the lot) than add .replace(/\s/g, '') to the end of the line
where the leading and trailing br's are replaced.

 

[Brian]

Brian wrote:...
Try something like:

var strCSVFile = 'Sunrise,-119.098,35.345,0.0<br>'
+ 'SwanDancer,-119.345,35.567,1.0<br>';

/* Remove any leading or trailing br elements */
strCSVFile = strCSVFile.replace(/(^<br>)|(<br>$)/g,'');

var arrayCSVFile = strCSVFile.split('<br>');
var recordElement;

/* arrayCSVFile is now an array with two elements:
*
* ['Sunrise,-119.098,35.345,0.0',
* 'SwanDancer,-119.345,35.567,1.0']
*/
for (var i=0, len=arrayCSVFile.length; i<len; i++){
arrayCSVFile = arrayCSVFile.split(',');

/* arrayCSVFile is still an array with two elements,
* but each is now an array of 4 elements:
*
* [
* ['Sunrise', '-119.098', '35.345', '0.0'],
* ['SwanDancer', '-119.345', '35.567', '1.0']
* ]
*/
for (var j=0, len2=arrayCSVFile.length; j<len2; j++){
recordElement = arrayCSVFile[j];

/* recordElement will be each element in turn, i.e.
* 'Sunrise', then '-119.098', then '35.345', and so on
*/

alert('Record: ' + (i+1) + ' of ' + len
+ '\nElement: ' + (j+1) + ' of ' + len2
+ '\nValue: ' + recordElement);
}
}

hey, Rob, I think you have dome something like this before (!) The
clarity of your formatting alone is helpful. I, also, split twice to
end up with CSV[][].

I ended up going a different direction at the end though. Rather than
make a single, flat line of elements, why not use the JS Object/perl
hash/ObjectiveC collection(?)/STL Map idiom. that is, and array of
objects, a series of name/value pairs. years ago I called it a
dictionary, or associative array (name/value pairs), but didn't use it
much. These days, it seems to have sprung into popularity, with
language support to just 'toss in' elements as needed (though I am not
using it that way here)

So the final lines of the my version turns into:
// Obj w/named fields, the result of processing the CSV
var csvDataObj = {};
csvDataObj.recArray = [];

// process each record
for ( index = 0; index < arrayCSVFile.length; index++ )
{
arrayCSVFile[ index ] = arrayCSVFile[ index ].split( ',' );

// build data container to pass out to other processes
var tRecObj = {};
tRecObj.recName = arrayCSVFile[index][0];
tRecObj.recLat = arrayCSVFile[index][1];
tRecObj.recLng = arrayCSVFile[index][2];
tRecObj.recAlt = arrayCSVFile[index][3];

csvDataObj.recArray.push( tRecObj);
}

// Now do something with arrayCSVFile[][]
gMyCore.processAllDevices( csvDataObj);

On the other end, I could "discover" the elements, but since its only
Javascript ;-) I use direct knowledge of the contents in the code.

I wrote it, worked the first time. So some things are going ok

 

[Brian]

Perhaps you need:
someVariable=strCSVFile.replace(/\s/g,'');

No need for "+", since you are using the "g" modifier. And why not
assign the result of the statement to a variable? (Unless you want to
destroy the original string.)

I would happily destry the original string! but, I am reticent to
admit, those simple replace's were failing silently. Haven't revisited
it quite yet.. on a deadline.. but will look soon

 

[Dr J R Stockton]

In comp.lang.javascript message

Perhaps you need:
someVariable=strCSVFile.replace(/\s/g,'');

No need for "+", since you are using the "g" modifier. And why not
assign the result of the statement to a variable? (Unless you want to
destroy the original string.)

Str.replace should have no effect on Str's existence. The .replace
method generates a new string, but does not destroy the old one.

AFAIK, the only type of Object which has Methods provided to change its
value is the Date Object.


I would expect, if there are instances of multiple /r, for the /r+
version to be slightly faster, since it calls for fewer replacements.
That could be implementation-dependent. A quick test shows a slight
gain in speed when using +.

It's a good idea to read the newsgroup and its FAQ. See below.

 

[mick white]

Str.replace should have no effect on Str's existence. The .replace
method generates a new string, but does not destroy the old one.

var StringA="A B C"
var StringA=StringA.replace(/\s/g,'');
alert(StringA);
But you're correct, /technically/.

Mick

 

[Dr J R Stockton]

In comp.lang.javascript message

Dr J R Stockton wrote:

var StringA="A B C"
var StringA=StringA.replace(/\s/g,'');
alert(StringA);
But you're correct, /technically/.

It is not the .replace that destroys "A B C", but the subsequent
assignment.

 

[Brian]

...
It's a good idea to read the newsgroup and its FAQ. See below.

Searching the three FAQs listed in your signature for the term
'replace' yields nothing at all about string replaces...

Rather than empathy or insight, a blind "read the FAQs" with no
specific pointer, and in this case FAQs that have no reference to my
problems. is in itself less than helpful.

page 526 of Javascript, the Definitive Guide, 4th Ed. does say that the
string replace() returns a new string with the replacement, but fails
to emphasize that the original argument is untouched.

On another note - Had this been C, would have checked the binary
contents of the array returned remotely immediately, by rote, in any
decent development envirnment. Since its web, and .js, and I'm still
getting used to it, I got caught by an annoying situation. Now I know.
I trust the thread will be helpful to someone someday.

 

[Dr J R Stockton]

In comp.lang.javascript message

Searching the three FAQs listed in your signature for the term
'replace' yields nothing at all about string replaces...

If I had wished to give you advice about your problem, I would have done
so in an article *directly* following-up to one of yours.

Rather than empathy or insight, a blind "read the FAQs" with no
specific pointer, and in this case FAQs that have no reference to my
problems. is in itself less than helpful.

If you have indeed searched all three URLs, you should have learned
quite a bit that can be useful to you in the future. You should also
have seen no case showing that the string parameter of .replace is
changed, and many cases in which the value of S.replace(a, b) is
assigned for use. You should also have seen a couple of references to
ECMA-262.

page 526 of Javascript, the Definitive Guide, 4th Ed. does say that the
string replace() returns a new string with the replacement, but fails
to emphasize that the original argument is untouched.

I'll take your word for that; but what do other pages say? However, if
it is clear that a value is RETURNed, is it not then unreasonable to
expect the original string (which is not an argument) to be altered?
That would be superfluous.


It's a good idea to read the newsgroup and its FAQ. See below.