This question already has answers here:
Why is my variable unaltered after I modify it inside of a function? - Asynchronous code reference
(7 answers)
Closed 6 years ago.
I try to write script to loop through object and return those which type is equal to custom data type set in HTML. Yet im unable to pass variable with array of objects to my for loop. Can you please tell me what am I doing wrong in this code? I receive:
Cannot read property 'length' of undefined
PS. It has to be done in raw JavaScript, no jQuery
var btn = document.getElementById("btn");
var przepisy;
function findData(data) {
var kuchnia = data.dataset.type;
var myRequest = new XMLHttpRequest();
myRequest.onreadystatechange = function() {
if (this.readyState === 4 && this.status == 200) {
przepisy = JSON.parse(myRequest.responseText);
}
};
myRequest.open('GET', 'js/przepisy.json');
myRequest.send();
for (i = 0; i < przepisy.length; i++) {
var results = "";
var obj = przepisy[i];
var type = przepisy.type;
if (type === kuchnia) {
results += obj.name;
document.write(results);
}
}
}
The issue is that you are making the call to your for loop before you get the data back, which is why the length is 0. You should just move the for loop into your response:
function findData(data) {
var kuchnia = data.dataset.type;
var myRequest = new XMLHttpRequest();
myRequest.onreadystatechange = function() {
if (this.readyState === 4 && this.status == 200) {
przepisy = JSON.parse(myRequest.responseText);
for(i = 0; i < Object.keys(przepisy).length; i++) {
var results = "";
var obj = przepisy[i];
var type = przepisy.type;
if(type === kuchnia) {
results += obj.name;
document.write(results);
}
}
}
};
myRequest.open('GET','js/przepisy.json');
myRequest.send();
}
I'm supposed to create a functions to test a URL for validity then functions to look for and return parts of the URL string based on location of certain characters (position would be unknown). FYI, I'm very new to programming but have been searching and trying many answers. My latest attempt uses below format (found in an answer) but still can not get anything but an empty string to display when I call the function.
When I run this in Chrome, and enter "http://www.niagaracollege.ca" or "http://lego.ca" even though I am entering a valid URL, I get a return of false.
function validURL(userInput)
{
input = new String(userInput);
if (input.indexOf("://") != -1 && input.lastIndexOf(".") != -1)
return true;
else
return false;
}
function findProtocol(userInput)
{
input = new String(userInput);
var result = input.substring(0, input.indexOf("://"));
return result;
}
function findServer(userInput)
{
input = new String(userInput);
var result = input.substring(input.indexOf("://") + 1 ,input.lastIndexOf("."));
return result;
}
function findDomain(userInput)
{
input = new String(userInput);
var result = input.substring(input.lastIndexOf(".") + 1);
return result;
}
function btnReadURL_onclick()
{
var userInput = document.getElementById("txtURL").value;
var outputBox = document.getElementById("txtOutput");
var URL = validURL(userInput);
if (URL = true)
{
var Part1 = findProtocol(userInput);
var Part2 = findServer(userInput);
var Part3 = findDomain(userInput);
outputBox.value = "Protocol: " + Part1 + "\nServer: " + Part2 +
"\nDomain: " + Part3;
}
else (URL == true)
outputBox.value = "Invalid URL";
}
Use a debugger to find out what you are getting in the userInput. The code is fine. It should work. See sample code below.
test = function() {
var test = "http://Test 2"
alert(test.substring(0, test.indexOf("://")))
}
You need to pass the value to the findProtocol method rather than DOM element
Replace
var userInput = document.getElementById("txtURL");
by
var userInput = document.getElementById("txtURL").value;
and replace
if (URL = true)
with
if( URL == true )
HELP! I am having an issue w/ one of my Javascript functions that has an inner Javascript function driven by an 'onreadystatechange'.
So all I am looking to do in my main JS code is figure out the value of jsonWR.SURG.EXIST_IND when this function runs. When the INNERretval alert runs, the value is correctly outputting to 1....this is what I expect. Then right before I return the value at the end of the main surgeryScheduled() function, ENDretval is saying the value is now 0.
I am sure I am missing something fundamental here, so can someone help me.
Plus, when surgeryScheduled() function is being called, I set a variable to the return value:
var q = 0;
q=surgeryScheduled(<someID>);
alert("q:"+q);
The above alert returns 1 when I would expect it to return 0 since ENDretval above was 0. What am I missing here??
function surgeryScheduled(srgnID){
var srgnPrsnlID = srgnID;
var sdt = document.getElementById('sdt').value;
var sdtc = sdt.toUpperCase();
var edt = document.getElementById('edt').value;
var edtc = edt.toUpperCase();
var paramString;
paramString =""
paramString += '^MINE^,'
+ srgnPrsnlID
+ ',^'
+ sdtc
+ '^,^'
+ edtc
+ '^'
var WRInfo = new XMLCclRequest();
//; Call the ccl progam and send the parameter string
WRInfo.open("GET", "CH_MP_HAVE_SURGERY_SCHED");
WRInfo.send(paramString);
//; Get the response
WRInfo.onreadystatechange = function () {
if (WRInfo.readyState == 4 && WRInfo.status == 200) {
var jsonWRResp = WRInfo.responseText;
if (jsonWRResp != undefined && jsonWRResp.length !=0) {
jsonWR = eval('(' + jsonWRResp + ')');
}
//; Make sure everything checks out, then return bool
if (jsonWR){
retval = jsonWR.SURG.EXIST_IND;
alert("INNERretval:"+retval);
}//;jsonWR
}//;WRInfo.readyState == 4 && WRInfo.status == 200
}//;WRInfo.onreadystatechange
alert("ENDRetval:"+retval);
return retval;
}
Ok, feeling stupid here, but wondering what the problem is here exactly.
Although the function works as it should, I get this JS Error in Opera. Not sure about other browsers...
Uncaught exception: TypeError: Cannot
convert
'document.getElementById("shoutbox_area"
+ moduleId)' to object
oElement = document.getElementById("shoutbox_area"
+ moduleId).childNodes;
Here is the relevant code:
function appendShout(XMLDoc)
{
var shoutData = XMLDoc.getElementsByTagName("item");
var oElement = [];
if (shoutData.length > 0)
{
var moduleId = shoutData[0].getAttribute("moduleid");
if (shoutData[shoutData.length - 1].getAttribute("lastshout") != "undefined")
{
for (var i = 0; i < shoutData.length; i++)
if (shoutData[i].firstChild.nodeValue != 0)
document.getElementById("shoutbox_area" + moduleId).innerHTML += shoutData[i].firstChild.nodeValue;
oElement = document.getElementById("shoutbox_area" + moduleId).childNodes;
var i = oElement.length;
while (i--)
{
if (i % 2 == 0)
oElement[i].className = "windowbg2";
else
oElement[i].className = "windowbg";
}
oElement[oElement.length - 2].style.borderBottom = "1px black dashed";
}
}
}
Can someone please help me to understand why it is giving me an error here:
oElement = document.getElementById("shoutbox_area" + moduleId).childNodes;
Can I not assign an array to the childNodes?
EDIT:
This JS Error occurs when I try and delete a shout. The JS function for deleting a shout is this:
function removeShout(shout, moduleID)
{
var shoutContainer = shout.parentNode.parentNode;
var send_data = "id_shout=" + shout.id;
var url = smf_prepareScriptUrl(smf_scripturl) + "action=dream;sa=shoutbox;xml;" + "delete_shout;" + "canmod=" + canMod[moduleID] + ";" + sessVar + "=" + sessId;
sendXMLDocument(url, send_data);
var shoutID = 0;
while (shoutID !== null)
{
var shoutID = document.getElementById(shout.parentNode.id);
var moduleID = shoutID.parentNode.getAttribute("moduleid");
if (shoutID.parentNode.lastChild)
{
var url = smf_prepareScriptUrl(smf_scripturl) + "action=dream;sa=shoutbox;xml;get_shouts=" + (shoutID.parentNode.lastChild.id.replace("shout_", "") - 1) + ";membercolor=" + memberColor[moduleID] + ";maxcount=" + maxCount[moduleID] + ";shoutboxid=" + shoutboxID[moduleID] + ";textsize=" + textSize[moduleID] + ";parsebbc=" + parseBBC[moduleID] + ";moduleid=" + moduleID + ";maxcount=" + maxCount[moduleID] + ";canmod=" + canMod[moduleID] + ";" + sessVar + "=" + sessId;
getXMLDocument(url, appendShout);
}
element = shoutID.parentNode.childNodes;
var i = element.length;
while (i--)
{
if (i % 2 == 0)
element[i].className = "windowbg2";
else
element[i].className = "windowbg";
}
shoutID.parentNode.removeChild(shoutID);
}
}
Am using the following functions for the sending and getting the XMLHttpRequest as you may have noticed already in the removeShout function above:
// Load an XML document using XMLHttpRequest.
function getXMLDocument(sUrl, funcCallback)
{
if (!window.XMLHttpRequest)
return null;
var oMyDoc = new XMLHttpRequest();
var bAsync = typeof(funcCallback) != 'undefined';
var oCaller = this;
if (bAsync)
{
oMyDoc.onreadystatechange = function () {
if (oMyDoc.readyState != 4)
return;
if (oMyDoc.responseXML != null && oMyDoc.status == 200)
{
if (funcCallback.call)
{
funcCallback.call(oCaller, oMyDoc.responseXML);
}
// A primitive substitute for the call method to support IE 5.0.
else
{
oCaller.tmpMethod = funcCallback;
oCaller.tmpMethod(oMyDoc.responseXML);
delete oCaller.tmpMethod;
}
}
};
}
oMyDoc.open('GET', sUrl, bAsync);
oMyDoc.send(null);
return oMyDoc;
}
// Send a post form to the server using XMLHttpRequest.
function sendXMLDocument(sUrl, sContent, funcCallback)
{
if (!window.XMLHttpRequest)
return false;
var oSendDoc = new window.XMLHttpRequest();
var oCaller = this;
if (typeof(funcCallback) != 'undefined')
{
oSendDoc.onreadystatechange = function () {
if (oSendDoc.readyState != 4)
return;
if (oSendDoc.responseXML != null && oSendDoc.status == 200)
funcCallback.call(oCaller, oSendDoc.responseXML);
else
funcCallback.call(oCaller, false);
};
}
oSendDoc.open('POST', sUrl, true);
if ('setRequestHeader' in oSendDoc)
oSendDoc.setRequestHeader('Content-Type', 'application/x-www-form-urlencoded');
oSendDoc.send(sContent);
return true;
}
Hopefully this is good enough, you can do a view source on it to see the actual HTML, but there are attributes that get added to the Shoutbox tags at runtime so as to be XHTML compliant, etc..
Please let me know if there is anything else you need?
Thanks :)
The code is breaking because shoutID is null in the second of these two lines, the second time through the loop:
var shoutID = document.getElementById(shout.parentNode.id);
var moduleID = shoutID.parentNode.getAttribute("moduleid");
The first of those lines is strange. Why not just use var shoutID = shout.parentNode;?
Also, the moduleId attribute seems to be nowhere around.
What are you trying to achieve with the while loop?
I wonder if is possible to get the text inside of a PDF file by using only Javascript?
If yes, can anyone show me how?
I know there are some server-side java, c#, etc libraries but I would prefer not using a server.
thanks
Because pdf.js has been developing over the years, I would like to give a new answer. That is, it can be done locally without involving any server or external service. The new pdf.js has a function: page.getTextContent(). You can get the text content from that. I've done it successfully with the following code.
What you get in each step is a promise. You need to code this way: .then( function(){...}) to proceed to the next step.
PDFJS.getDocument( data ).then( function(pdf) {
pdf.getPage(i).then( function(page){
page.getTextContent().then( function(textContent){
What you finally get is an string array textContent.bidiTexts[]. You concatenate them to get the text of 1 page. Text blocks' coordinates are used to judge whether newline or space need to be inserted. (This may not be totally robust, but from my test it seems ok.)
The input parameter data needs to be either a URL or ArrayBuffer type data. I used the ReadAsArrayBuffer(file) function in FileReader API to get the data.
Note: According to some other user, the library has updated and caused the code to break. According to the comment by async5 below, you need to replace textContent.bidiTexts with textContent.items.
function Pdf2TextClass(){
var self = this;
this.complete = 0;
/**
*
* #param data ArrayBuffer of the pdf file content
* #param callbackPageDone To inform the progress each time
* when a page is finished. The callback function's input parameters are:
* 1) number of pages done;
* 2) total number of pages in file.
* #param callbackAllDone The input parameter of callback function is
* the result of extracted text from pdf file.
*
*/
this.pdfToText = function(data, callbackPageDone, callbackAllDone){
console.assert( data instanceof ArrayBuffer || typeof data == 'string' );
PDFJS.getDocument( data ).then( function(pdf) {
var div = document.getElementById('viewer');
var total = pdf.numPages;
callbackPageDone( 0, total );
var layers = {};
for (i = 1; i <= total; i++){
pdf.getPage(i).then( function(page){
var n = page.pageNumber;
page.getTextContent().then( function(textContent){
if( null != textContent.bidiTexts ){
var page_text = "";
var last_block = null;
for( var k = 0; k < textContent.bidiTexts.length; k++ ){
var block = textContent.bidiTexts[k];
if( last_block != null && last_block.str[last_block.str.length-1] != ' '){
if( block.x < last_block.x )
page_text += "\r\n";
else if ( last_block.y != block.y && ( last_block.str.match(/^(\s?[a-zA-Z])$|^(.+\s[a-zA-Z])$/) == null ))
page_text += ' ';
}
page_text += block.str;
last_block = block;
}
textContent != null && console.log("page " + n + " finished."); //" content: \n" + page_text);
layers[n] = page_text + "\n\n";
}
++ self.complete;
callbackPageDone( self.complete, total );
if (self.complete == total){
window.setTimeout(function(){
var full_text = "";
var num_pages = Object.keys(layers).length;
for( var j = 1; j <= num_pages; j++)
full_text += layers[j] ;
callbackAllDone(full_text);
}, 1000);
}
}); // end of page.getTextContent().then
}); // end of page.then
} // of for
});
}; // end of pdfToText()
}; // end of class
I couldn't get gm2008's example to work (the internal data structure on pdf.js has changed apparently), so I wrote my own fully promise-based solution that doesn't use any DOM elements, queryselectors or canvas, using the updated pdf.js from the example at mozilla
It eats a file path for the upload since i'm using it with node-webkit.
You need to make sure you have the cmaps downloaded and pointed somewhere and you nee pdf.js and pdf.worker.js to get this working.
/**
* Extract text from PDFs with PDF.js
* Uses the demo pdf.js from https://mozilla.github.io/pdf.js/getting_started/
*/
this.pdfToText = function(data) {
PDFJS.workerSrc = 'js/vendor/pdf.worker.js';
PDFJS.cMapUrl = 'js/vendor/pdfjs/cmaps/';
PDFJS.cMapPacked = true;
return PDFJS.getDocument(data).then(function(pdf) {
var pages = [];
for (var i = 0; i < pdf.numPages; i++) {
pages.push(i);
}
return Promise.all(pages.map(function(pageNumber) {
return pdf.getPage(pageNumber + 1).then(function(page) {
return page.getTextContent().then(function(textContent) {
return textContent.items.map(function(item) {
return item.str;
}).join(' ');
});
});
})).then(function(pages) {
return pages.join("\r\n");
});
});
}
usage:
self.pdfToText(files[0].path).then(function(result) {
console.log("PDF done!", result);
})
Just leaving here a full working sample.
<html>
<head>
<script src="https://npmcdn.com/pdfjs-dist/build/pdf.js"></script>
</head>
<body>
<input id="pdffile" name="pdffile" type="file" />
<button id="btn" onclick="convert()">Process</button>
<div id="result"></div>
</body>
</html>
<script>
function convert() {
var fr=new FileReader();
var pdff = new Pdf2TextClass();
fr.onload=function(){
pdff.pdfToText(fr.result, null, (text) => { document.getElementById('result').innerText += text; });
}
fr.readAsDataURL(document.getElementById('pdffile').files[0])
}
function Pdf2TextClass() {
var self = this;
this.complete = 0;
this.pdfToText = function (data, callbackPageDone, callbackAllDone) {
console.assert(data instanceof ArrayBuffer || typeof data == 'string');
var loadingTask = pdfjsLib.getDocument(data);
loadingTask.promise.then(function (pdf) {
var total = pdf._pdfInfo.numPages;
//callbackPageDone( 0, total );
var layers = {};
for (i = 1; i <= total; i++) {
pdf.getPage(i).then(function (page) {
var n = page.pageNumber;
page.getTextContent().then(function (textContent) {
//console.log(textContent.items[0]);0
if (null != textContent.items) {
var page_text = "";
var last_block = null;
for (var k = 0; k < textContent.items.length; k++) {
var block = textContent.items[k];
if (last_block != null && last_block.str[last_block.str.length - 1] != ' ') {
if (block.x < last_block.x)
page_text += "\r\n";
else if (last_block.y != block.y && (last_block.str.match(/^(\s?[a-zA-Z])$|^(.+\s[a-zA-Z])$/) == null))
page_text += ' ';
}
page_text += block.str;
last_block = block;
}
textContent != null && console.log("page " + n + " finished."); //" content: \n" + page_text);
layers[n] = page_text + "\n\n";
}
++self.complete;
//callbackPageDone( self.complete, total );
if (self.complete == total) {
window.setTimeout(function () {
var full_text = "";
var num_pages = Object.keys(layers).length;
for (var j = 1; j <= num_pages; j++)
full_text += layers[j];
callbackAllDone(full_text);
}, 1000);
}
}); // end of page.getTextContent().then
}); // end of page.then
} // of for
});
}; // end of pdfToText()
}; // end of class
</script>
Here's some JavaScript code that does what you want using Pdf.js from http://hublog.hubmed.org/archives/001948.html:
var input = document.getElementById("input");
var processor = document.getElementById("processor");
var output = document.getElementById("output");
// listen for messages from the processor
window.addEventListener("message", function(event){
if (event.source != processor.contentWindow) return;
switch (event.data){
// "ready" = the processor is ready, so fetch the PDF file
case "ready":
var xhr = new XMLHttpRequest;
xhr.open('GET', input.getAttribute("src"), true);
xhr.responseType = "arraybuffer";
xhr.onload = function(event) {
processor.contentWindow.postMessage(this.response, "*");
};
xhr.send();
break;
// anything else = the processor has returned the text of the PDF
default:
output.textContent = event.data.replace(/\s+/g, " ");
break;
}
}, true);
...and here's an example:
http://git.macropus.org/2011/11/pdftotext/example/
Note: This code assumes you're using nodejs. That means you're parsing a local file instead of one from a web page since the original question doesn't explicitly ask about parsing pdfs on a web page.
#gm2008's answer was a great starting point (please read it and its comments for more info), but needed some updates (08/19) and had some unused code. I also like examples that are more full. There's more refactoring and tweaking that could be done (e.g. with await), but for now it's as close to that original answer as it could be.
As before, this uses Mozilla's PDFjs library. The npmjs package is at https://www.npmjs.com/package/pdfjs-dist.
In my experience, this doesn't do well in finding where to put spaces, but that's a problem for another time.
[Edit: I believe the update to the use of .transform has restored the whitespace as it originally behaved.]
// This file is called myPDFfileToText.js and is in the root folder
let PDFJS = require('pdfjs-dist');
let pathToPDF = 'path/to/myPDFfileToText.pdf';
let toText = Pdf2TextObj();
let onPageDone = function() {}; // don't want to do anything between pages
let onFinish = function(fullText) { console.log(fullText) };
toText.pdfToText(pathToPDF, onPageDone, onFinish);
function Pdf2TextObj() {
let self = this;
this.complete = 0;
/**
*
* #param path Path to the pdf file.
* #param callbackPageDone To inform the progress each time
* when a page is finished. The callback function's input parameters are:
* 1) number of pages done.
* 2) total number of pages in file.
* 3) the `page` object itself or null.
* #param callbackAllDone Called after all text has been collected. Input parameters:
* 1) full text of parsed pdf.
*
*/
this.pdfToText = function(path, callbackPageDone, callbackAllDone) {
// console.assert(typeof path == 'string');
PDFJS.getDocument(path).promise.then(function(pdf) {
let total = pdf.numPages;
callbackPageDone(0, total, null);
let pages = {};
// For some (pdf?) reason these don't all come in consecutive
// order. That's why they're stored as an object and then
// processed one final time at the end.
for (let pagei = 1; pagei <= total; pagei++) {
pdf.getPage(pagei).then(function(page) {
let pageNumber = page.pageNumber;
page.getTextContent().then(function(textContent) {
if (null != textContent.items) {
let page_text = "";
let last_item = null;
for (let itemsi = 0; itemsi < textContent.items.length; itemsi++) {
let item = textContent.items[itemsi];
// I think to add whitespace properly would be more complex and
// would require two loops.
if (last_item != null && last_item.str[last_item.str.length - 1] != ' ') {
let itemX = item.transform[5]
let lastItemX = last_item.transform[5]
let itemY = item.transform[4]
let lastItemY = last_item.transform[4]
if (itemX < lastItemX)
page_text += "\r\n";
else if (itemY != lastItemY && (last_item.str.match(/^(\s?[a-zA-Z])$|^(.+\s[a-zA-Z])$/) == null))
page_text += ' ';
} // ends if may need to add whitespace
page_text += item.str;
last_item = item;
} // ends for every item of text
textContent != null && console.log("page " + pageNumber + " finished.") // " content: \n" + page_text);
pages[pageNumber] = page_text + "\n\n";
} // ends if has items
++self.complete;
callbackPageDone(self.complete, total, page);
// If all done, put pages in order and combine all
// text, then pass that to the callback
if (self.complete == total) {
// Using `setTimeout()` isn't a stable way of making sure
// the process has finished. Watch out for missed pages.
// A future version might do this with promises.
setTimeout(function() {
let full_text = "";
let num_pages = Object.keys(pages).length;
for (let pageNum = 1; pageNum <= num_pages; pageNum++)
full_text += pages[pageNum];
callbackAllDone(full_text);
}, 1000);
}
}); // ends page.getTextContent().then
}); // ends page.then
} // ends for every page
});
}; // Ends pdfToText()
return self;
}; // Ends object factory
Run in the terminal:
node myPDFfileToText.js
Updated 02/2021
<script src="https://npmcdn.com/pdfjs-dist/build/pdf.js"></script>
<script>
function Pdf2TextClass(){
var self = this;
this.complete = 0;
this.pdfToText = function(data, callbackPageDone, callbackAllDone){
console.assert( data instanceof ArrayBuffer || typeof data == 'string' );
var loadingTask = pdfjsLib.getDocument(data);
loadingTask.promise.then(function(pdf) {
var total = pdf._pdfInfo.numPages;
//callbackPageDone( 0, total );
var layers = {};
for (i = 1; i <= total; i++){
pdf.getPage(i).then( function(page){
var n = page.pageNumber;
page.getTextContent().then( function(textContent){
//console.log(textContent.items[0]);0
if( null != textContent.items ){
var page_text = "";
var last_block = null;
for( var k = 0; k < textContent.items.length; k++ ){
var block = textContent.items[k];
if( last_block != null && last_block.str[last_block.str.length-1] != ' '){
if( block.x < last_block.x )
page_text += "\r\n";
else if ( last_block.y != block.y && ( last_block.str.match(/^(\s?[a-zA-Z])$|^(.+\s[a-zA-Z])$/) == null ))
page_text += ' ';
}
page_text += block.str;
last_block = block;
}
textContent != null && console.log("page " + n + " finished."); //" content: \n" + page_text);
layers[n] = page_text + "\n\n";
}
++ self.complete;
//callbackPageDone( self.complete, total );
if (self.complete == total){
window.setTimeout(function(){
var full_text = "";
var num_pages = Object.keys(layers).length;
for( var j = 1; j <= num_pages; j++)
full_text += layers[j] ;
console.log(full_text);
}, 1000);
}
}); // end of page.getTextContent().then
}); // end of page.then
} // of for
});
}; // end of pdfToText()
}; // end of class
var pdff = new Pdf2TextClass();
pdff.pdfToText('PDF_URL');
</script>
For all the people who actually want to use it on a node server:
/**
* Created by velten on 25.04.16.
*/
"use strict";
let pdfUrl = "http://example.com/example.pdf";
let request = require('request');
var pdfParser = require('pdf2json');
let pdfPipe = request({url: pdfUrl, encoding:null}).pipe(pdfParser);
pdfPipe.on("pdfParser_dataError", err => console.error(err) );
pdfPipe.on("pdfParser_dataReady", pdf => {
//optionally:
//let pdf = pdfParser.getMergedTextBlocksIfNeeded();
let count1 = 0;
//get text on a particular page
for (let page of pdf.formImage.Pages) {
count1 += page.Texts.length;
}
console.log(count1);
pdfParser.destroy();
});
It is possible but:
you would have to use the server anyway, there's no way you can get content of a file on user computer without transferring it to server and back
I don't thing anyone has written such library yet
So if you have some free time you can learn pdf format and write such a library yourself, or you can just use server side library of course.