How to empty an Array in a Script

Question

I have a script that uses AJAX/PHP/SQL to query data and pushes it into an array with a bunch of IF's statements. The changeData function is called every 6 seconds. The first query I return I have 6 arrays. The second time i send a request, my push array(IsVacant1) is double and went to 12. after a while, I have over 500 arrays going into my .each statement.

How do I 'clear' this every time I make a request so that I am not adding arrays? Any help is most appreciated.

function changeData() {
        isPaused = true;


        var mydata0 = null;
        $.post('php/ProductionChange.php', {
                    'WC': cc
                }, function(data) { // This is Where I use an AJAX call into a php file.

                    mydata0 = data; // This takes the array from the call and puts it into a variable 
                    var pa = JSON.parse(mydata0); // This parses the data into arrays and elements  
                    var temp = {};
                    var bayData = '';

                    if (pa != null) {

                        for (var i = 0; i <= pa.length - 1; i++) {

                            var job = pa[i][0];
                            var shipdate = pa[i][1];
                            var status = pa[i][2];
                            var name = pa[i][3];
                            var EnclLoc = pa[i][13];
                            var Enclsize = pa[i][14];
                            var backpan = pa[i][15];
                            var percentCom = pa[i][16];
                            var IsVisible = pa[i][17];
                            var png = pa[i][18];
                            var WorkC = pa[i][20];
                            baydata = 'bayData' + i + '';
                            temp = {
                                job, shipdate, name, EnclLoc, Enclsize, backpan, percentCom, IsVisible, png, WorkC, status
                            };
                            isVacant1.push({
                                baydata: temp
                            });   
                        }
                    } else {
                        ii = 1;
                        //alert("There are no more job numbers in this bay location. Thank you. ");
                    }
                    $.each(isVacant1, function(key, value) {

                                var job = value.baydata.job;
                                var ship = value.baydata.shipdate;
                                var name = value.baydata.name;
                                var encl = value.baydata.EnclLoc;
                                var EnclSize = value.baydata.EnclLoc;
                                var percentCom = value.baydata.percentCom;
                                var backpan = value.baydata.backpan;
                                var PngLogo = value.baydata.png;
                                var IsVisible = value.baydata.IsVisible;
                                var WorkC = value.baydata.WorkC;
                                var status = value.baydata.status;
                                var p = WorkC;
                                WorkC = (WorkC < 10) ? ("0" + WorkC) : WorkC;

                                //// remember  if the encl location matches the workcell cell then do stuff based on that....... hint encl image not hiding becase of duplicate 17s

                                if (((encl == p) || (backpan == p)) && job != 123) {
                                    $('#WC' + p).show();
                                    document.getElementById("bayData" + p).innerHTML = name + ' ' + ship; // Work Cell  Name and Ship Date
                                    document.getElementById("bayData" + p + "a").innerHTML = job; // Work cell Job Number
                                    document.getElementById("percentCom" + p).innerHTML = percentCom + '%'; // Work Cell Percent Complete                       
                                } else {
                                    $('#WC' + p).hide();

So your question is how to empty an Array? Set the length to 0. If instead you wish to remove n items from the beginning of an Array, you can use splice, arr.splice(0, n) — Paul S.
– Paul S., Commented Sep 1, 2015 at 16:38
Thank you, still trying to find out where to actually pa.length to zero. — ENGR024
– ENGR024, Commented Sep 1, 2015 at 16:45
do you mean something like temp.splice(0,n)={stuff, stuff,}; ????? — ENGR024
– ENGR024, Commented Sep 1, 2015 at 16:50
@dave the 'pa' doesnt have the previous rows; its the isVacant1.. Need to find the location where to put this to zero. Every where i put it, it does set it to zero and still adds the array... any ideas? — ENGR024
– ENGR024, Commented Sep 1, 2015 at 17:03

Community · Accepted Answer · 2017-05-23 11:52:09Z

2

From your question it looks like you want to clear the isVacant1 array. In your ajax callback just put isVacant1 = []; as the first line. Like this

       function(data) { // This is Where I use an AJAX call into a php file.
                isVacant1 = [];

                mydata0 = data; // This takes the array from the call and puts it into a variable 
                var pa = JSON.parse(mydata0); // This parses the data into arrays and elements  
                var temp = {};
                var bayData = '';

                ..................

From your code it's not clear how you are declaring/initializing isVacant1 so i have suggested isVacant1 = [] otherwise you can also use isVacant1.length = 0.

You can also take a look here How do I empty an array in JavaScript?

edited May 23, 2017 at 11:52

CommunityBot

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answered Sep 1, 2015 at 17:10

Ashraf Purno

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2 Comments

ENGR024 Over a year ago

This was successful. Thank you .. I declared it as var isVacant1=[]; so I used isVacant1=[]; in the location you specified and it worked.

Ashraf Purno Over a year ago

In that case you can use isVacant1.length = 0; instead of isVacant1 = []; which might be more safer depending on your situation. For more details regarding this please go through the link mentioned in the answer.

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