Javascript resetting an array - javascript

I'm having with some very strange behaviour when I try to reset an array; eg:
where data is an array. I'll try and include only the relevant code here but basically what I;m doing is on each iteration of my program I'm populating the array with updated values and the array then is used in another function. But when I reset the array the function appears to get the values on the first iteration but none afterwards.
However when I don't reset the array then the function gets the values, but also the older values. I don't want this, as I only want the new updated values only. This is a code snippet:
var buffer = [['1',[0]],['2',[0]],['3',[0]],['4',[0]]];
var dataset = [];
ws.onmessage = function(evt){
var distances = JSON.parse(;
for(var i=0; i<buffer.length; i++) {
if(buffer[i][0] == distances.miles) {
The function uses the dataset array to redraw a chart.
I've tried to keep it simple here, but the full function is here.
I really don't know what's causing this unexpected behaviour.
console.log(dataset) shows the new updated values, but somehow dataset.length=0; is preventing the updated array to be used by the draw() function. As without the resetting of the array the array can be used by the draw() function.
I've tried to not reset the array but instead get the last 4 elements and put them in a new array and then send them to the draw(), but still the same odd behaviour:
x = dataset.slice(-4);
But if I don't do that or don't clear the array, then draw() render a 'wrong' chart. I can't see what is wrong.
THE problem somehow seems to reside with the resetting of the array and that because of this it means the draw() function appears to be called only once at the first iteration.
Please, Please help

You don't need to set length at all. To clear a list of all value, just set it to an empty list:
dataset = [];

Looking at your code, I'm not sure, but why do you even have dataset? You don't ever read anything out of it, and you say you want to clear it every time thru the array.
Do you mean do to something like:
for(var i=0; i<buffer.length; i++) {
if(buffer[i][0] == distances.miles) {
draw(dataset); // draw outside the loop, using dataset.


How do I split/slice a leaflet L.layerGroup into mutliple L.layerGroup(s)?

I'm using leafletjs to draw a line from marker to marker. But the markers are grouped into sets, each with its own name. I get the data from MySQL with PHP and create;
var OBJMarkerList = L.layerGroup([W0DLK01,W0DLK02,W0DLK03,W0DLK04,W0DLK05,WA0TJT01,WA0TJT02,WA0TJT03,WA0TJT04,WA0TJT05,WA0TJT06,WA0TJT07,WA0TJT08,WA0TJT09,]);
Notice the name changes.
But I need to pass it into a function one part at a time in order to change the color of the line. So while I have the above OBJMarkerList what I really need is;
var W0DLKOBJMarkerList = L.layerGroup([W0DLK01,W0DLK02,W0DLK03,W0DLK04,W0DLK05,]);
And another for the other set of values, WA0TJTOBJMarkerList.
I created an array of the names;
const allnameBounds = (['W0DLKOBJMarkerList','WA0TJTOBJMarkerList']);
But its literally just the names and the function (below) will not accept it as input to convert to the x,y coordinates I need.
function connectTheDots(data){
var c = [];
for(i in data._layers) {
var x = data._layers[i];
var y = data._layers[i]._latlng.lng;
c.push([x, y]);
return c;
How can I split the L.layerGroup into two or any number of parts based on the variable names given? There will usually be more than just two, this is a simplified example.
I tried iterating over the allnameBounds array in all the usual ways and while the looping works to extract the name, the function does not process it like the leaflet object it is.
I also went back to the MySQL/PHP and tried to create a stand alone for each name, that's fine but I still need another list of the L.layerGroup names to iterate over.
Spliting or slicing the combined seemed the only answer. I just don't know how to get there.
Can someone give me a better way or show me how to split the overall list?

Problems with code listing unique items in a list and copying them into new worksheet

I'm trying to run the following code on a spreadsheet. The column of names is the 4th column. I'm attempting to run through that list of names, pushing each new unique name to an array (listOfNames), and then add a new worksheet (NamesList), and finally add the array to cell A1 of the new worksheet. When I run the code below, all I get is a blank popup with an OK and Cancel button. When I view the log, it is blank as well. I'm quite new at this, and I feel like I'm missing something obvious... just not sure what it is. Am I misunderstanding something specific to GAS rather than JS?
var sheet = SpreadsheetApp.getActiveSheet();
var listOfNames = new Array ();
function copyNames() {
var data = sheet.getDataRange().getValues();
for (i=0; i<=sheet.getLastRow(); i++){
var tempName = sheet.getDataRange(i,4).getValue();
for (i=0; i<=listOfNames.length; i++){
if (tempName != listOfNames[i]){
Edit: I'm starting to see that this will push values multiple times to the list... so maybe it's just back to the drawing board all together. I have found other code that would create a list of unique elements, but wasn't really sure how that code worked. I thought I'd try to figure it out myself so I'd at least understand it.
EDIT 2: Ok... I tried some new code, but I'm still getting a blank message box, and nothing on the log. I wasn't sure if having i be the iterator for a for loop within a for loop was a bad thing, so I switched it to j. Also, I know there's the remove duplicates example, and have been looking at that, but am unsure why one needs to use join.
function copyNames() {
var sheet = SpreadsheetApp.getActiveSheet();
var listOfNames = new Array ();
var data = sheet.getDataRange().getValues();
for (i=2; i<=data.length; i++){ //starting at 2 because first row is a header
var tempName = data[i][4];
for (j=0; j<=listOfNames.length+1; j++){
if (tempName != listOfNames[j]){
As far as I understand you went help instead of a ready solution, so here you go.
Try to avoid using global variables. Keep all your variables inside of your functions. Otherwise you will have issues when you add more functions to your spreadsheet. Your Code should start like this:
function copyNames() {
var sheet = SpreadsheetApp.getActiveSheet();
var data = sheet.getDataRange().getValues();
var listOfNames = new Array ();
Try to decrease the amount of service calls to spreadsheet. it takes several seconds for your script to go to your sheet and take the values. Instead of doing it each time, take these values once and push them in to a variable.
In your case, you already did that, however did not use that variable and kept using service calls. Check this line:
var data = sheet.getDataRange().getValues();
Now all of the data on that sheet is in a variable called data.
is the same as
The only difference is that in the first case it will take approximately 2 seconds to get that value, while in the second case only a few milliseconds.
Same goes for
Either call it once and push it into a variable and use that, or in your case just use
listOfNames is an empty array, so it's length is 0.
This line
for (i=0; i<=listOfNames.length; i++)
will not even run, as both i and listOfNames.length is 0.
That is why you logger does not give any output. Your script never get's to that line.
You do not have a variable called ListOfEDs, therefore your last two rows of code just give an error. Your script does not know what is ListOfEDs as it doesn't exist.
Hope this helps.

Parsing a JSON object of arrays gives different results in IE9

I am working on creating a HighCharts graph from a DataTable table.
What I do is iterate over the the rows and columns of the table, convert the strings (we use different thousand separators from the US) to numbers and save them into an object called item. the object has two values item["name"] which is the name of the series and item["data"] which is the data for the series. I then use the .push method to add these objects to an array to send to a Highcharts options object to create the plot. In the case below, I only have three series, but the problem always occurs. The LineOptions is an options-object for the HighCharts Graph.
function plotLineOrBar(type){
var jsonData = [];
var xaxis = $('#masters_table table').find('thead th:not(:first-child)').map(function(){
return $(this).html();
$('#masters_table table tbody tr').each(function(){
item = {};
item["name"] = $(this).find('td:first-child').html();
item["data"] = $(this).find('td:not(:first-child)').map(function(){
return parseInt($(this).html().replace(/\./g, "").replace('',0),10);
console.log(jsonData[0]["name"]); // send the 0th name to console
console.log(jsonData[1]["name"]); // send the 1st name to console
console.log(jsonData[2]["name"]); // send the 2nd name to console
LineOptions.series = (jsonData);
LineOptions.xAxis.categories = xaxis;
var chart = new Highcharts.Chart(LineOptions);
(The name of the series should be 2320,2321,2336)
In Chrome, the resulting console.log is:
and the corresponding data to each series prints out correctly and everything works flawlessly.
In IE9, the resulting console.log is:
LOG: 2336
LOG: 2336
LOG: 2336
i.e., only the last series gets printed into the array. The result is three series with perfectly overlapping curves, since they have the same data.
I have searched and searched for answers, wrapped by brain around but I can still not figure out what I am doing wrong. I assume though, that my error is a simple one (I hope).
As previously wrote in the comment (for future reference), just define the item variable inside of the loop function, instead of using a "global" one (var item = {} instead of item = {}). This is because in IE9 it seems to be passed by reference, and thus you're pushing the very same object, updated three times (changing its values from iteration to iteration).
by the way it seems that the other browser you're using, it is creating a new variable every time you use .push and I'm not sure that's the "standard" behavior. One point to IE9!

Angular Js stuck in inserting the array values after sorting

Hello guys i am stuck in angular js.
What i have to do is to show the steps of selectionSort and the code i made is
var myApp = angular.module('myApp',[]);
var arraymain = [];
myApp.controller('myController',function($scope) {
$scope.array2 = [];
$scope.selectionSort = function(list) {
temp2 = list;
for(i=0; i<n-1; i++) { //need to do n-2 passes
//finding mining index
for(j=i+1;j<n;j++){//ith position: elements from i till n-1 candidates
i_min=j; //update the index of minimim element
alert(temp); //It shows as needed
$scope.array2.push(temp2); //Here i am having problem it saves the sorted final array i.e the last every time of loop but i want to save current array on every outer loop execution
return list;
Sorry for my bad English.
It's not clear what you need to do. I'm pretty sure you've got a real mess on your hands beyond your main problem, and using Angular is only making it worse.
If your goal is to console.log the state of the array at each step of the selectionSort outer loop, then you need to run console.log at the bottom of each loop.
The first thing that looks fishy suspicious is:
If you run console.log(array2) at each step of the loop as I suggested, you need this line to be instead:
$scope.array2 = temp2;
That way, you overwrite array2, which holds the state of the array at each iteration of the for loop. Then you log it. Appending each state to a larger array, and then running console.log on each item in that array is not the best way to do this.
But, I'm not sure that's what your problem is.

Changing the variables of a class in OOP in javascript

I have defined a function called Node which stores the properties of nodes in a graph data structure. The function is something like this:
function Node(){
this.outEdges = [];
this.inEdges = [];
where the inEdges and outEdges store elements of type Edge which is another function I have defined. During the program these arrays are filled with elements.
At some point in my code I need to reset these two arrays so I write:
nodes[i].outEdges.length = 0;
nodes[i].inEdges.length = 0;
where nodes is an array of elements of type Node and I am accessing an element in a for loop.
The problem is, after setting outEdges and inEdges to 0, I expected them to be [] in the nodes[i] property list. However, when I output nodes[i] into console, the outEdges and inEdges still have the elements in them. The stranger thing is that when I output nodes[i].outEdges to console, it prints [] , which is correct, but clicking on [ ] again opens the list of the elements! I can't really figure out why the nodes[i] variables don't change?
That happens (probably) because the browser prints out the empty array but by the time you check it, it has content again. So when you click to expand the browser shows the actual content.
As you can see the values [1,3,7] were added after the command console.log(o) but they are shown on the screen (even though the length shown is 0).
You're not supposed to set the length field. Just re-initialize them:
nodes[i].outEdges = [];
nodes[i].inEdges = [];
Edit: My bad, setting the length should work. It does work for me on Chrome at least. However, I still think it's safer and better style to re-init.
Just create a new object with the same name
nodes[i].outEdges = new Array();