I'm passing a string which looks something like: "John.Doe.100.Newbie-David.Miller.250.Veteran-" to the SplitDatabase function which splits the string appropriately and assigns the values to the UserDataEntry object. The UserDataEntry object is then pushed in to the global UserData array which is supposed to store all the user data.
For some reason though, the UserData.push(UserDataEntry) part seems to be overwriting previous data in the UserData array. The alert in the 1st loop shows the correct data as it loops, but alert in the second loop at the bottom just shows the last record over and over again.
I'm not sure why this is?
var UserData = [];
function SplitDatabase(result) {
var RawUsers = result.split('-');
var UserDataEntry = {};
for (var i = 0; i < (RawUsers.length - 1); i++) {
var tempUserData = RawUsers[i].split('.');
for (var x = 0; x < (tempUserData.length); x++) {
switch (x) {
case 0:
UserDataEntry.firstname = tempUserData[x];
break;
case 1:
UserDataEntry.lastname = tempUserData[x];
break;
case 2:
UserDataEntry.points = tempUserData[x];
break;
case 3:
UserDataEntry.rank = tempUserData[x];
UserData.push(UserDataEntry);
alert(UserData[i].firstname);
break;
}
}
}
for (var i = 0; i < (UserData.length); i++) {
alert(UserData[i].firstname);
}
}
Calling push will not copy your object, because JavaScript Objects are passed by reference: you're pushing the same Object as every array entry.
You can fix this easily by moving the var UserDataEntry = {}; inside the loop body, so that a new object is created each loop iteration:
for (var x = 0; x < (tempUserData.length); x++) {
var UserDataEntry = {};
Put your line var UserDataEntry = {} inside the for loop.
Right now, you only have one object, and you're setting each part of the array to that object. You overwrite the members in your loop.
If you create a new object inside the loop, you'll add all new members in to the array.
Related
I had to remove same data in array.
I found this code and its work exactly the way i want but I can not understand part of this code.
please explain this code and WHAT IS THIS >>> a[this[i]] <<<
Array.prototype.unique = function() {
var a = {}; //new Object
for (var i = 0; i < this.length; i++) {
if (typeof a[this[i]] == 'undefined') {
a[this[i]] = 1;
}
}
this.length = 0; //clear the array
for (var i in a) {
this[this.length] = i;
}
return this;
};
Please see the comments before each line that explain that line of code
//added unique function to prototype of array so that all array can have unique //function access
Array.prototype.unique = function() {
//creating a temp object which will hold array values as keys and
//value as "1" to mark that key exists
var a = {}; //new Object
//this points to the array on which you have called unique function so
//if arr = [1,2,3,4] and you call arr.unique() "this" will point to
//arr in below code iterating over each item in array
for (var i = 0; i < this.length; i++) {
//idea is to take the value from array and add that as key in a so
//that next time it is defined. this[i] points to the array item at
//that index(value of i) //and a[this[i]] is adding a property on a
//with name "this[i]" which is the value //at that index so if value
//at that index is lets say 2 then a[this[i]] is //referring to
//a["2"].thus if 2 exists again at next index you do not add it to a
//again as it is defined
if (typeof a[this[i]] == 'undefined') {
a[this[i]] = 1;
}
}
this.length = 0; //clear the array
//now in a the properties are unique array items you are just looping
//over those props and adding it into current array(this) in which
//length will increase every //time you put a value
for (var i in a) {
this[this.length] = i;
}
//at the end returning this which is the modified array
return this;
};
//Edit
stored value of a[this[i]] is 1 for all the keys in a it will be one.
you start with
arr = [1,2,3,2,3,4];
when you call arr.unique
the code in the first loop creates a something like this
a = {
"1":1,
"2":1,
"3":1,
"4":1
}
so you can see that only unique values are as properties in a.
Now in the for-in loop you are just taking the keys of a(ie 1,2,3,4) and adding it to the array(this).
Hope this helps let me know if you need more details
a[this[i]] =>
this[i] -> get i element from current object, in this case it's Array.
a[] -> get element from var a at position specified in [], in this case what value is inside this[i]
i just wanted to create a Dynamic Object in JS, but the Object only saves the last Element of the foor loop. Heres my Code :
for(var i = 0; i < req.session.userObjekt.length; i++) {
var userObjekt = {
[req.session.userObjekt[i].User]: {
Data : req.session.userObjekt[i].Data,
Admin: req.session.userObjekt[i].Admin
}
};
}
When i output in the for loop i get the correct result (7 Users + Properties)
When i output out of the for loop, i only get the last User + Properties.
How to save all Elements from the for loop in my Object?
Thanks in advance.
Because you assign to your userObjekt a new object in each iteration. Move out your object declaration from the for loop body
var userObjekt = { };
for(var i = 0; i < req.session.userObjekt.length; i++) {
userObjekt[req.session.userObjekt[i].User] = {
Data : req.session.userObjekt[i].Data,
Admin: req.session.userObjekt[i].Admin
};
}
You can create an array outside of loop and just push the objects in it later on you can use the declared and filled array:
var objektArr = [];
for(var i=0; i<req.session.userObjekt.length; i++) {
var userObjekt = {
[req.session.userObjekt[i].User]: {
Data : req.session.userObjekt[i].Data,
Admin: req.session.userObjekt[i].Admin
},
};
objektArr.push(userObjekt);
}
console.log(objektArr);
I am trying to build an array that should look like this :
[
[{"name":"Mercury","index":0}],
[{"name":"Mercury","index":1},{"name":"Venus","index":1}],
[{"name":"Mercury","index":2},{"name":"Venus","index":2},{"name":"Earth","index":2}],
...
]
Each element is the concatenation of the previous and a new object, and all the indexes get updated to the latest value (e.g. Mercury's index is 0, then 1, etc.).
I have tried to build this array using the following code :
var b = [];
var buffer = [];
var names = ["Mercury","Venus","Earth"]
for (k=0;k<3;k++){
// This array is necessary because with real data there are multiple elements for each k
var a = [{"name":names[k],"index":0}];
buffer = buffer.concat(a);
// This is where the index of all the elements currently in the
// buffer (should) get(s) updated to the current k
for (n=0;n<buffer.length;n++){
buffer[n].index = k;
}
// Add the buffer to the final array
b.push(buffer);
}
console.log(b);
The final array (b) printed out to the console has the right number of objects in each element, but all the indexes everywhere are equal to the last value of k (2).
I don't understand why this is happening, and don't know how to fix it.
This is happening because every object in the inner array is actually the exact same object as the one stored in the previous outer array's entries - you're only storing references to the object, not copies. When you update the index in the object you're updating it everywhere.
To resolve this, you need to create new objects in each inner iteration, or use an object copying function such as ES6's Object.assign, jQuery's $.extend or Underscore's _.clone.
Here's a version that uses the first approach, and also uses two nested .map calls to produce both the inner (variable length) arrays and the outer array:
var names = ["Mercury","Venus","Earth"];
var b = names.map(function(_, index, a) {
return a.slice(0, index + 1).map(function(name) {
return {name: name, index: index};
});
});
or in ES6:
var names = ["Mercury","Venus","Earth"];
var b = names.map((_, index, a) => a.slice(0, index + 1).map(name => ({name, index})));
Try this:
var names = ["Mercury","Venus","Earth"];
var result = [];
for (var i=0; i<names.length; i++){
var _temp = [];
for(var j=0; j<=i; j++){
_temp.push({
name: names[j],
index:i
});
}
result.push(_temp);
}
console.log(result)
try this simple script:
var b = [];
var names = ["Mercury","Venus","Earth"];
for(var pos = 0; pos < names.length; pos++) {
var current = [];
for(var x = 0; x < pos+1; x++) {
current.push({"name": names[x], "index": pos});
}
b.push(current);
}
I m new a web developer and i face up the following problem:
"Cannot read property 'length' of undefined"
my code:
var data=();
for(var i;i<parseInt(window.localStorage["numOfInserts"]);i++){
data["category_name"]=localStorage.getItem(("category_name_"+i).toString());
data["category_id"]=localStorage.getItem(("category_id_"+i).toString());
data["provider_name"]=localStorage.getItem(("provider_name_"+i).toString());
data["provider_id"]=localStorage.getItem(("provider_id_"+i).toString());
data["appointment_date"]=localStorage.getItem(("appointment_date_"+i).toString());
data["appointment_time"]=localStorage.getItem(("appointment_time_"+i).toString());
}
$scope.allAppointments=dataArray;
for(var i=0;i<dataArray.length;i++){
$scope.showme[i]=false;
}
After some research I understand that the problem caused to the fact that data is an array but I try to turn it to json, but
var data ={};
gives me the same error as before.
Please Help me
I think this is what you're looking for, see code comments:
// Create an array using []
var data = [];
// Get the count once
var count = parseInt(window.localStorage["numOfInserts"]);
// Be sure to initialize `i` to 0
for (var i = 0; i < count; i++) {
// Create an object to push onto the array, using the information
// from local storage. Note that you don't need toString() here.
// Once we've created the object (the {...} bit), we push it onto
// the array
data.push({
category_name: localStorage.getItem("category_name_"+i),
category_id: localStorage.getItem("category_id_"+i),
provider_name: localStorage.getItem("provider_name_"+i),
provider_id: localStorage.getItem("provider_id_"+i),
appointment_date: localStorage.getItem("appointment_date_"+i),
appointment_time: localStorage.getItem("appointment_time_"+i)
});
}
This does the same thing, it's just more verbose and so could help you understand more clearly what's going on:
// Create an array using []
var data = [];
// Get the count once
var count = parseInt(window.localStorage["numOfInserts"]);
// Be sure to initialize `i` to 0
for (var i = 0; i < count; i++) {
// Create an object to push onto the array
var obj = {};
// Fill it in from local storage. Note that you don't need toString() here.
obj.category_name = localStorage.getItem("category_name_"+i);
obj.category_id = localStorage.getItem("category_id_"+i);
obj.provider_name = localStorage.getItem("provider_name_"+i);
obj.provider_id = localStorage.getItem("provider_id_"+i);
obj.appointment_date = localStorage.getItem("appointment_date_"+i);
obj.appointment_time = localStorage.getItem("appointment_time_"+i);
// Push the object onto the array
data.push(obj);
}
You need to create an array(dataArray before the loop), and create a new object in each iteration and set the property values for that object then add the object to the array like below
var dataArray = [],
data, numOfInserts = parseInt(window.localStorage["numOfInserts"]);
for (var i = 0; i < numOfInserts; i++) {
data = {};
data["category_name"] = localStorage.getItem(("category_name_" + i).toString());
data["category_id"] = localStorage.getItem(("category_id_" + i).toString());
data["provider_name"] = localStorage.getItem(("provider_name_" + i).toString());
data["provider_id"] = localStorage.getItem(("provider_id_" + i).toString());
data["appointment_date"] = localStorage.getItem(("appointment_date_" + i).toString());
data["appointment_time"] = localStorage.getItem(("appointment_time_" + i).toString());
dataArray.push(data)
}
$scope.allAppointments = dataArray;
for (var i = 0; i < dataArray.length; i++) {
$scope.showme[i] = false;
}
It looks like you're trying to create an associative array, so the first line should indeed be
var data = {};
The next part is fine, but then it looks like you want to enumerate the keys
for(var i=0;i<Object.keys(data).length;i++){
$scope.showme[i]=false;
}
I am almost there with this but cannot seem to get this functionality going as planned.
I have two arrays: keyArray and ValArray;
What I am trying to do is to have a function pass two arguments (keyArr,valArr). Within this function, a parent object is declared and a (for-loop) loops through the passed argument's length (in this case "keyArr") creates new objects according the length of the passed argument. And then, the newly created objects are assigned the keys and values.
The issue is that I am able to create the parent object"mObj", and children Objects to "mObj", but am only able to assgin keys and values to the first child object "obj0" not rest of the children objects correctly. At the end of the code, this is what I would like to get:
enter code heremObj.obj0.firstname = John;
mObj.obj0.lastname = superfly;
mObj.obj0.email = "john.superfly#yahoo.com";
mObj.obj1.firstname = John;
mObj.obj1.lastname = superfly;
mObj.obj1.email = "john.superfly#yahoo.com";
mObj.obj2.firstname = John;
mObj.obj2.lastname = superfly;
mObj.obj2.email = "john.superfly#yahoo.com";
This is my code:
var keyArr = ["firstname","lastname","email"];
var valArr = ["John","Superfly","jsuperfly#yahoo.com"];
function test(keys,vals) // FUNCTION TEST ACCEPTS TWO ARGS
{
var mObj = {}; // PARENT OBJECT
var len = (keys.length); //ARGUMENT KEY'S LENGTH
for(var i=0; i<len; i++)
{
mObj["obj" + i] = {}; //CHILDREN OBJECTS ARE CREATED TO PARENT "mObj" OBJECT
mObj["obj" + i][keys[i]] = vals[i]; //KEYS AND VALUES ARE ASSIGNED HERE
}
alert(mObj.obj1.firstname); // CURRENTLY RETURNS "UNDEFINED"
}
test(keyArr,valArr);
Any insight into this would highly be appreciated.
Thank you.
Seems like this is what you need. This code will create as many child objects as the length of keyArr and valArr arrays. Although no idea why you would need it.
var keyArr = ["firstname", "lastname", "email"];
var valArr = ["John", "Superfly", "jsuperfly#yahoo.com"];
function test(keys, vals) {
var mObj = {},
i, j, len = keys.length;
for (i = 0; i < len; i++) {
mObj["obj" + i] = {};
for (j = 0; j < len; j++) {
mObj["obj" + i][keys[j]] = vals[j];
}
}
alert(mObj.obj1.firstname);
}
console.log( test(keyArr, valArr) );