EDIT: the problem I came across was that I did not know that js arrays are treated as objects and any as so are referenced not copied. If you were interested in simply reversing a js array you can use...reverse();
I thought I would be able to simply do the following in javascript
var originalArray = [1,2,3,5,8,13];
var originalArrayCOPY = originalArray;
console.log ("new copy = "+originalArrayCOPY);
for(var zyx = 0; zyx <6; zyx++){
var xyz = 5-zyx;
originalArray[zyx] = originalArrayCOPY[xyz];
}
console.log("original now "+originalArray);
console.log("copy ="+originalArrayCOPY);
But my results are so strange that I feel I must not understand javascript at all!!
new copy = 1,2,3,5,8,13
original now 13,8,5,5,8,13,
copy =13,8,5,5,8,13,
I can-t see why this wouldn-t work and I honestly am not sure why the COPY of the original array is changed at all.
If I could at least name the problem I could ask google, also if you tell me the name of the problem I will rename by SO question.
use this:
var originalArray = [1,2,3,5,8,13];
var originalArrayCOPY = originalArray.slice();
console.log ("new copy = "+originalArrayCOPY);
for(var zyx = 0; zyx <6; zyx++){
var xyz = 5-zyx;
originalArray[zyx] = originalArrayCOPY[xyz];
}
console.log("original now "+originalArray);
console.log("copy ="+originalArrayCOPY);
'=' copy references and slice() will produce a new copy of the array.
see : https://developer.mozilla.org/en/docs/Web/JavaScript/Reference/Global_Objects/Array/slice
Related
I have an array of objects called objectArray1. I would like to set a second variable, objectArray2, to the value of this first array, and then be able to change it independently.
Here is the code I tried:
var objectArray1 = [
{number:1, color:'red'},
{number:4, color:'blue'}
];
var objectArray2 = objectArray1;
objectArray2[0].number = 7;
console.log(objectArray1);
However, as you can see from the above snippet, changing a value in objectArray2 also changes the same value in objectArray1 (the 1 changes to a 7).
I found some other questions on stackoverflow about this, such as Setting one object equal to another object with the assignment operator in Javascript, but they are all just about objects and not arrays of objects, so I haven't been able to apply them to my case.
To try and fix my issue, I tried some new code which I hoped would work better:
var objectArray1 = [
{number:1, color:'red'},
{number:4, color:'blue'}
];
var objectArray2 = [];
for (i = 0; i < objectArray1.length; i++) {
objectArray2.push(objectArray1[i]);
}
objectArray2[0].number = 7;
console.log(objectArray1);
However, the same thing still happens (the 1 still changes to a 7). How do I solve this?
To do a clone of this you just need to do
var objectArray1 = [
{number:1, color:'red'},
{number:4, color:'blue'}
];
var objectArray2 = JSON.parse(JSON.stringify(objectArray1));
And this will actually create a new copy of the objects and not just reference them and you should be able to work on the separately like you want.
U just need to use a spread operator.
var objectArray1 = [
{number:1, color:'red'},
{number:4, color:'blue'}
];
var objectArray2 = JSON.parse(JSON.stringify(objectArray1 ));
objectArray2[0].number = 7;
console.log(objectArray1);
SOLVED, Thank you! I needed to specify the index.
I am trying to push a set of variables into an array from user input.
Without using push it is working fine;
var inputStart = addAppointment.inputStart.value;
var inputEnd = addAppointment.inputEnd.value;
var appointmentArr = [];
appointmentArr = {start:inputStart, end:inputEnd};
document.write(appointmentArr.start);
document.write(appointmentArr.end);
however, when I try to push the variables it returns undefined;
var inputStart = addAppointment.inputStart.value;
var inputEnd = addAppointment.inputEnd.value;
var appointmentArr = [];
appointmentArr.push({start:inputStart, end:inputEnd});
document.write(appointmentArr.start);
document.write(appointmentArr.end);
Can anyone explain why this is happening?
As far as I am aware I need to use push because I eventually want to create a new, populated index number every time the user inputs data, so any help is greatly appreciated.
Thanks in advance
You are accessing array.
So, the document.write part should be like this
document.write(appointmentArr[0].start);
document.write(appointmentArr[0].end);
Since appointmentArr is an array, you should fisrt take appointmentArr[0] to access the first element of the array.
After you push the value, the appointmentArr becomes, [{start:inputStart, end:inputEnd}]
Since, it is an array you cannot access object keys directly, you have to take specific index element and then can access them using appointmentArr[index]
var inputStart = 'inputStart';
var inputEnd = 'inputEnd';
var appointmentArr = [];
appointmentArr.push({start:inputStart, end:inputEnd});
document.write(appointmentArr[0].start + ' ');
document.write(appointmentArr[0].end);
Please run the above snippet
You re-assigned your variable as Object.
var appointmentArr = [];
appointmentArr = {start:inputStart, end:inputEnd};
This code overwrite appointmentArr from Array [] to Object { start:inputStart, end:inputEnd }
And in the second code:
var appointmentArr = [];
appointmentArr.push({start:inputStart, end:inputEnd});
You modify appointmentArr from Array [] to Array [ {start:inputStart, end:inputEnd} ].
So, following code will work as you want.
document.write(appointmentArr[0].start);
document.write(appointmentArr[0].end);
I am looking for some help, I am working on a piece of code for a client, the client currently have their analytics tag hardcoded to the page with all the key values being sent.
We are in the process of converting them to a new analytics platform using a tag management system, they have been able to update the majority of their platforms to create an object that the new analytics platform can reference but as this site is managed by a 3rd party they are unable to get this resolved in time for our release.
I have managed to successfully pull the tag and split the tag in to parameters:
var x = $('img[alt="MI_TAG"]').attr("src");
x.split("&");
Which creates the array:
1:"109=jsp.searchFlights.initial"
2:"117=Flight Only Journey"
3:"206=02/11/2017"
4:"208=03/11/2017"
5:"212=ALL"
What I want to do is take these array strings to create an object call "mi", like so:
109:"jsp.searchFlights.initial"
117:"Flight Only Journey"
204:""
205:""
206:"02/11/2017"
208:"03/11/2017"
Can someone help?
Thanks all for your help, I have managed to take some of the advice here and create the object and see it logging out:
var x = $('img[alt="MI_TAG"]').attr("src");
var split = x.split("&");
var arrayLength = split.length;
var arr = [];
var i = 0;
do {
arr.push(split[i].replace('=',':'));
arr.toString();
console.log(arr);
i += 1;
} while (i < arrayLength);
let mi = {};
arr.forEach(item=>{
let tempArr = item.split(':');
mi[tempArr[0]] = tempArr[1];
})
console.log(mi);
The issue I now seem to be facing is scope, I want my object to be globally referenceable, how do I do that?
From your array, use reduce - split on the = sign in your string, and create the object:
let newObject = arr.reduce((obj, item) => {
let parts = item.split("=");
obj[parts[0]] = parts[1];
return obj;
}, {});
Assuming you are using at least ECMAScript 5.1 you could use Array.prototype.forEach() to iterate over your array and produce the object.
let myArray = ["109=jsp.searchFlights.initial", "117=Flight Only Journey", "206=02/11/2017", "208=03/11/2017",
"212=ALL"];
let myObject = {};
myArray.forEach(item=>{
let tempArr = item.split('=');
myObject[tempArr[0]] = tempArr[1];
})
console.log(myObject);
Produces:
{
"109": "jsp.searchFlights.initial",
"117": "Flight Only Journey",
"206": "02/11/2017",
"208": "03/11/2017",
"212": "ALL"
}
I imported json data into google scripts with:
var doc = Utilities.jsonParse(txt);
I can access most of the objects like such...
var date = doc.data1.dateTime;
var playerName = doc.data1.playerName;
var playerId = doc.data1.playerID;
var teamNumber = doc.data2.personal.team;
A bunch of objects I need to access have numbers as object names...
doc.data2.personal.team.87397394.otherdata
doc.data2.personal.team.87397395.otherdata
doc.data2.personal.team.87397396.otherdata
doc.data2.personal.team.87397397.otherdata
...but when I try to read the data with...
var teamId = doc.data2.personal.team.87397394;
... I get an error "Missing ; before statement."
I tried this...
var teamId = doc.data2.personal.team[87397394];
... and get "teamId undefined" in the log.
I also tied this with the same result...
var teamId = doc.data2.personal.team[+'6803761'];
I can read in the names as strings very easily with "For In", but can't get to the objects themselves. Every example I've found so far uses the brackets so I'm stumped what to try next.
Thank you!
Brian
UPDATE
I used this per your suggestions to get the object name into a variable and using the variable in brackets. No error but var test remains "undefined"...
for(var propertyName in doc.data2.personal.team) {
// propertyName is what you want
// you can get the value like this: myObject[propertyName]
Logger.log (propertyNames);
var test = doc.data2.personal.team[propertyName];
}
The log shows the object names, as expected...
87397394
87397395
87397396
87397397
I'm thinking it's a bug in Google's implementation. Here is an example if anyone wants to verify it. test will return undefined...
function myFunction1() {
var txt = UrlFetchApp.fetch("http://www.hersheydigital.com/replays/replays_1.json").getContentText();
var doc = Utilities.jsonParse(txt);
for(var propertyName in doc.datablock_battle_result.vehicles) {
Logger.log (propertyName);
var test = doc.datablock_battle_result.vehicles[propertyName];
}
}
The problem seems to be in the Utitlies.jsonParse. The following works fine
var txt = UrlFetchApp.fetch("http://www.hersheydigital.com/replays/replays_1.json").getContentText();
var doc = JSON.parse(txt);
for(var propertyName in doc.datablock_battle_result.vehicles) {
var vehicle = doc.datablock_battle_result.vehicles[propertyName];
Logger.log('Vehicle id is ' + propertyName);
Logger.log('Vehicle value is ' + JSON.stringify(vehicle));
break;
}
This is annoying me.
I'm setting an array in beginning of the doc:
var idPartner;
var myar = new Array();
myar[0] = "http://example.com/"+idPartner;
And I'm getting a number over the address, which is the id of partner. Great. But I'm trying to set it without success:
$.address.change(function(event) {
idPartner = 3;
alert(idPartner);
}
Ok. The alert is giving me the right number, but isn't setting it.
What's wrong?
Changing the value of the variable does not re-set the values within the array. That is just something javascript can't do automatically. You would have to re-generate the array for it to have the new id. Could you add the id to the value where you use the array instead of pre-setting the values in the array containing the id?
Edit: For example, you would do:
var myArray = [];
var myId = 0;
myArray[0] = "http://foo.com/id/";
and when you need to use a value from the array, you would do this:
var theVal = myArray[0] + myId;
Try this:
var myvar = ["http://site.com/"];
$.address.change(function(event) {
myvar[1] = 3;
}
then use myvar.join () where you need the full url.
The problem here is that at the line
myar[0] = "http://site.com/"+idPartner;
..you perform a string concatenation, meaning you copy the resulting string into the array at index position 0.
Hence, when later setting idPartnerit won't have any effect on the previously copied string. To avoid such effect you can either always construct the string again when the idPartnervariable updates or you create an object and you evaluate it when you need it like...
var MyObject = function(){
this.idPartner = 0; //default value
};
MyObject.prototype.getUrl = function(){
return "http://site.com/" + this.idPartner;
};
In this way you could use it like
var myGlblUrlObj = new MyObject();
$.address.change(function(event){
myGlblUrlObj.idPartner = ... /setting it here
});
at some later point you can then always get the correct url using
myGlblUrlObj.getUrl();
Now obviously it depends on the complexity of your situation. Maybe the suggested array solution might work as well, although I prefer having it encapsulated somewhere in an object for better reusability.
myar[0] = "http://site.com/" + idPartner;
After this line, myar[0] = "http://site.com/undefined" and it has nothing to do with the variable idPartner no more.
So, after that changing the value of idPartner will affect the value of myar[0].
You need to change the value of myar[0] itself.