We Keep Coding

How to Execute ajax call after the scroller reaches the bottom

I'm correcting working on lazy loading for 200 array of objects and APIs are provided to me to extract JSON from the server (by passing index, row count as parameter for the get AJAX and on response I get the data and the Boolean of whether there are more rows or not). But the problem is that initially I was able to get the data of 10 from the 200 but while I set the scroll function on the div it displays duplicate data which are already appended on the div. Stucked in this problem for a day.
Hope you guys shed some light on me.
var listgen = (function() {
var mc = {};
mc.startindex = 1;
mc.rowcount = 10;
mc.hasmorerows = false;
mc.entity = "requests"
//Declared variables:
mc.initComponent = function() {
var entity = "requests";
mc.callAjaxForList(mc.entity, mc.startindex, mc.rowcount);
$("#reqbody").on('scroll', function() {
if (mc.hasmorerows && ($(this)[0].scrollHeight <= $(this).scrollTop() + $(this).innerHeight())) {
console.log('reached')
mc.callAjaxForList(mc.entity, mc.startindex, mc.rowcount);
}
console.log("scroll");
})
}
mc.callAjaxForList = function(entity, startindex, rowcount) {
var options = {
"list_info": {
"row_count": rowcount,
"start_index": startindex
}
}
$("#reqbody").addClass("loading");
$.ajax({
url: "/data/" + entity,
data: {
"input_data": JSON.stringify(options)
},
contentType: "application/json; charset=utf8",
type: "GET",
success: function(json) {
mc.hasmorerows = json.list_info.has_more_rows
mc.onDataLoading(json);
},
});
}
mc.onDataLoading = function(json) {
//this is where i append the data from the json
mc.startindex += mc.rowcount
}
return mc;
})()
listgen.initComponent();

Scroll is a very high-frequent event, so I think that you have several ajax calls with same data before actually your onDataLoading called, and range incremented. So I whould add mutex.
// ...
mc.loaging = false; // mutex
$("#reqbody").on('scroll', function(){
if(mc.hasmorerows && ($(this)[0].scrollHeight<=$(this).scrollTop()+$(this).innerHeight())){
console.log('reached')
if (!mc.loading) // add check here
mc.callAjaxForList(mc.entity,mc.startindex,mc.rowcount);
}
console.log("scroll");
})
}
mc.callAjaxForList= function(entity,startindex,rowcount){
// ...
mc.loading = true;
$.ajax({
// ...
success:function(json){
mc.hasmorerows=json.list_info.has_more_rows
mc.onDataLoading(json) ;
mc.loading = false;
},
error: ()=> mc.loading = false
});
}
So our mc.loading will tell us if ajax already completed (do not forget to reset it's value on ajax error)

How do I capture an aborted call or is setting the timeout to 0 correct?

I have a JavaScript client that works in Chrome and Firefox, but fails in IE. Looking at the network trace in the IE debugger it shows that multiple of the AJAX calls have been aborted.
I've been able to get around it by setting the timeout to 0. I'd like to know if this is the correct way to handle my requests being aborted? Basically what could go wrong?
My initial thought was that I should capture and resend on error, and if multiple resubmits do not result in a completed request, finally alert the user. I'd still like to know how to do this even if the setTimeout is the proper way to address my immediate issue.
Also the application will process an excel workbook of addresses, call a web service to add some data to them and then allow the user to download the enhanced file.
This is what I have so far, first in the app.js
var requestWithFeedback = function (args) {
$(".loader").removeClass('hidden');
var oldConfig = args.config || function () { };
args.config = function (xhr) {
xhr.setRequestHeader("Authorization", "Bearer " + localStorage.token);
oldConfig(xhr);
extract: extract;
};
var deferred = m.deferred();
setTimeout(function () { // <== This solved in IE, but is this the way to handle this?
m.request(args).then(deferred.resolve, function(err){
if (err === "Invalid token!"){
m.route('/');
}
})}, 0);
$(".loader").addClass('hidden');
return deferred.promise;
}
From the model.js
app.MarkedAddresses.ProcessAddressBatch = function () {
var requestData = {
Addresses: app.MarkedAddresses.vm.addresses
}
return requestWithFeedback({
method: "POST"
, url: "API/server.ashx"
, data: requestData
, deserialize: function (value) { return value; }
})
.then(function (value) {
var responseJSON = $.parseJSON(value);
$.merge(app.MarkedAddresses.vm.results, responseJSON)
app.MarkedAddresses.vm.currentRecord(app.MarkedAddresses.vm.results.length);
app.MarkedAddresses.vm.progress(Math.max(app.MarkedAddresses.vm.progress(), ~~(app.MarkedAddresses.vm.currentRecord() / app.MarkedAddresses.vm.totalRecords() * 100)));
m.redraw(); //Force redraw for progress bar
return value;
},
function (error) { console.log(error) } // <== I thought error would show up here, but I never hit a breakpoint here.
);
}
Added loops
function process_wb(wb) {
app.MarkedAddresses.vm.results.length = 0;
$('.descending').removeClass("descending");
$('.ascending').removeClass("ascending");
app.MarkedAddresses.vm.progress(.1);
m.redraw();
var header = mapHeader(wb);
var addressJSON = to_json(wb, header);
app.MarkedAddresses.vm.totalRecords(addressJSON.length);
for (var i = 0; (i < addressJSON.length + 1) ; i += 1000) {
app.MarkedAddresses.vm.addresses = addressJSON.slice(i, Math.min(((i) + 1000), addressJSON.length));
app.MarkedAddresses.vm.response(new app.MarkedAddresses.vm.processAddressBatch());
}
}
Why isn't the error triggered in the section of the code?
It seems like I should add a deferred section here, but anything I've tried has been a syntax error.

Catch exception in JS

I've got next code that fills page with data I get from server every 10 sec:
var refreshFunction = function() {
//get data from server
$.get("<c:out value="${baseURL}"/>/js/getCounts", function(data) {
vardata = data;
});
if (vardata != null) {
//divide
countArray = vardata.split("/");
//if server returns "-" or new array with new structure
if ((vardata == "-" || length != countArray.length)
&& !(document.getElementById('requestForm') instanceof Object)) {
//reload
location.reload();
clearInterval(refreshId);
} else {
//fill page with data
for (var j = 0; j <= countArray.length; j++) {
console.log(countArray[j]);
$('#badge_' + (j + 1)).text(countArray[j]);
}
}
}
};
$(document).ready(function() {
refreshId = setInterval(refreshFunction, 10000);
});
The code works, but if I open application and then turn off my server, script will never stop. I'm having
Failed to load resource: net::ERR_CONNECTION_REFUSED
How can I catch it and stop the script after that? I was trying to wrap code blocks with try and catch(e), but doesn't help.

Since the AJAX request is executed asynchronously, wrapping your code in try ... catch will not catch the exception. The exception happens after your code has finished executing.
You should handle the .fail case on the object returned by $.get to avoid seeing that error reported on the console:
var jqxhr = $.get("<c:out value="${baseURL}"/>/js/getCounts", function() {
vardata = data;
})
.done(function() {
alert( "second success" );
})
.fail(function() {
alert( "error" );
})
.always(function() {
alert( "finished" );
});
As a side note, you should put the complete body of your function inside the call back in $.get. Otherwise, you'll always be running your code with the old dataset, not the new one.
This problem doesn't show up in your code in the first execution because vardata is probably undefined and in Javascript land, undefined != null is false.

Office.context.document.getFileAsync throwing errors

I am getting a very strange issue whereby when I try to extract the word document as a compressed file for processing in my MS Word Task Pane MVC app the third time, it will blow up.
Here is the code:
Office.context.document.getFileAsync(Office.FileType.Compressed, function (result) {
if (result.status == "succeeded") {
var file = result.value;
file.getSliceAsync(0, function (resultSlice) {
//DO SOMETHING
});
} else {
//TODO: Service fault handling?
}
});
The error code that comes up is 5001. I am not sure how to fix this.
Please let me know if you have any thoughts on this.
Additional Details:

From MSDN:
No more than two documents are allowed to be in memory; otherwise the
getFileAsync operation will fail. Use the File.closeAsync method to
close the file when you are finished working with it.
Make sure you call File.closeAsync before you read the file again - that could explain the issue you are seeing.
More at: https://msdn.microsoft.com/en-us/library/office/jj715284.aspx

I have an example about how to use this API correctly. Actually the current example in the MSDN is not very correct. This code is tested in Word.
// Usually we encode the data in base64 format before sending it to server.
function encodeBase64(docData) {
var s = "";
for (var i = 0; i < docData.length; i++)
s += String.fromCharCode(docData[i]);
return window.btoa(s);
}
// Call getFileAsync() to start the retrieving file process.
function getFileAsyncInternal() {
Office.context.document.getFileAsync("compressed", { sliceSize: 10240 }, function (asyncResult) {
if (asyncResult.status == Office.AsyncResultStatus.Failed) {
document.getElementById("log").textContent = JSON.stringify(asyncResult);
}
else {
getAllSlices(asyncResult.value);
}
});
}
// Get all the slices of file from the host after "getFileAsync" is done.
function getAllSlices(file) {
var sliceCount = file.sliceCount;
var sliceIndex = 0;
var docdata = [];
var getSlice = function () {
file.getSliceAsync(sliceIndex, function (asyncResult) {
if (asyncResult.status == "succeeded") {
docdata = docdata.concat(asyncResult.value.data);
sliceIndex++;
if (sliceIndex == sliceCount) {
file.closeAsync();
onGetAllSlicesSucceeded(docdata);
}
else {
getSlice();
}
}
else {
file.closeAsync();
document.getElementById("log").textContent = JSON.stringify(asyncResult);
}
});
};
getSlice();
}
// Upload the docx file to server after obtaining all the bits from host.
function onGetAllSlicesSucceeded(docxData) {
$.ajax({
type: "POST",
url: "Handler.ashx",
data: encodeBase64(docxData),
contentType: "application/json; charset=utf-8",
}).done(function (data) {
document.getElementById("documentXmlContent").textContent = data;
}).fail(function (jqXHR, textStatus) {
});
}
You may find more information from here:
https://github.com/pkkj/AppForOfficeSample/tree/master/GetFileAsync
Hope this could help.

Additional to Keyjing Peng's answer (which I found very helpful, thanks!) I thought I'd share a variation on the encodeBase64, which you don't want to do if you are uploading via REST to SharePoint. In that case you want to convert the byte array to a Uint8Array. Only then could I get it into a SharePoint library without file corruption.
var uArray = new Uint8Array(docdata);
Hope this helps someone, couldn't find this info anywhere else online...

See this link
http://msdn.microsoft.com/en-us/library/office/jj715284(v=office.1501401).aspx
it contains this example method:
var i = 0;
var slices = 0;
function getDocumentAsPDF() {
Office.context.document.getFileAsync("pdf",{sliceSize: 2097152}, function (result) {
if (result.status == "succeeded") {
// If the getFileAsync call succeeded, then
// result.value will return a valid File Object.
myFile = result.value;
slices = myFile.sliceCount;
document.getElementById("result").innerText = " File size:" + myFile.size + " #Slices: " + slices;
// Iterate over the file slices.
for ( i = 0; i < slices; i++) {
var slice = myFile.getSliceAsync(i, function (result) {
if (result.status == "succeeded") {
doSomethingWithChunk(result.value.data);
if (slices == i) // Means it's done traversing...
{
SendFileComplete();
}
}
else
document.getElementById("result").innerText = result.error.message;
});
}
myFile.closeAsync();
}
else
document.getElementById("result2").innerText = result.error.message;
});
}
change "pdf" to "compressed" and the method call doSomethingWithChunk() needs to be created and should probably do something like this:
function base64Encode(str) {
return btoa(encodeURIComponent(str).replace(/%([0-9A-F]{2})/g, function (match, p1) {
return String.fromCharCode('0x' + p1);
}));
}
I use this technique to successfully save to Azure blob storage.
Obviously you should rename the method as well.

Test if localStorage is full

I am learning about localStorage and it sounds like each browser gives a domain 5MB.
I wrote this code to cache the data returned from an ajax call and it works. But how do I test to see if localStorage is full? If there is no localStorage space available I imagine that the ajax request should be made again.
Here's my code:
if ( localStorage && localStorage.getItem('myGithub') ) {
console.log('if statement');
console.log( JSON.parse( localStorage.getItem( 'myGithub') ) );
render( JSON.parse( localStorage.getItem( 'myGithub') ) );
}
else {
console.log('else statment');
$.ajax({
url : 'https://api.github.com/users/xxxxxxxxx',
dataType : 'json',
success : function (data) {
if ( localStorage ) {
localStorage.setItem( 'myGithub', JSON.stringify(data) );
}
console.log(data);
render(data);
}
});
}
//Render method for printing the results to the <body> element.
//Returns html from the ajax call or from localStorage.
function render (myObjx) {
var results = '';
for (var prop in myObjx) {
results += '<p>data.' + prop + ' = ' + myObjx[prop] + '</p>';
}
var printData = $('body').html(results);
return printData;
};

You can use the below approach. You can change it as per your requirement.
function checkAvailable(){
var test = 'test';
try {
localStorage.setItem(test, test);
localStorage.removeItem(test);
return true;
} catch(e) {
return false;
}
}
// And you call below to check the availablity
if(checkAvailable() === true){
// available
}else{
// unavailable
}