Hope you have been a good day. I want to ask you a question. Here is it:
So I have an object and I get values from it with Underscore.js (I will give you an example without using underscore.js to getting values).
After I get values, it puts numbers that are bigger than 0. I think it sorts bigger than smaller.
I want values exactly how they are at the object before I take them.
Here is an image for you
Here is the code
tmpReport.forEach(element => {
const tmpVal = [];
console.log("element: ", element);
tmpValList.push(_.values(element));
console.log('tmpValList: ', tmpValList);
});
Here is the code without using underscore.js:
tmpReport.forEach(element => {
const tmpVal = [];
console.log("element: ", element);
Object.entries(element).forEach(([key, value]) => {
tmpVal.push(value);
});
tmpValList.push(tmpVal);
console.log('tmpValList: ', tmpValList);
});
So any help will be appreciated. Thank you!
In JavaScript, the order of object entries is not guaranteed.
If you want to put specific entries at specific indices in your array you have to do that manually.
For example:
tmpVal[0] = element['Cell damage by placing'];
...
tmpVal[4] = element['time'];
tmpVal[5] = element['toplan'];
You can only achieve that if you are aware of your object keys. As far as I know there is now generic way to keep the initial order as there is no order to begin with.
The best you can do in that case is use a lexicographic order and sort your keys accordingly.
Related
I have a map of id => value that I want to sort by value.
But no matter what I do, it always gets sorted by id.
Basically I have a sorted map on server side that I send to javascript via json.
{"3":"Apple","2":"Banana","1":"Orange"}
After de-serialization I get
{
1:"Orange",
2:"Banana",
3:"Apple"
}
And no matter what I try, it seems to stay in this order. Is it possible in javascript to force a non ascending sort order with interger keys?
var json = '{"3":"Apple", "2":"Banana", "1":"Orange"}';
var data = $.parseJSON(json);
for (var ix in data) {
console.log(ix + ": " + data[ix]);
}
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
You should not rely on objects key order for these reasons.
I personally would recommend you to either use a Map, or to build an Array instead.
Below is an example to build an array from your source: for simplicity, I've added a key property to make the sorting easier.
Note: I'm using Array.from to build the array, which is taking the length from the parsed object keys length, and using the callback to init the object inline.
var json = '{"3":"Apple", "2":"Banana", "1":"Orange"}';
// Parse the json string.
const parsed = JSON.parse(json);
// Acquire the keys length
const length = Object.keys(parsed).length;
// Build an array of objects ordered in the same way it came.
const result = Array.from({length}, (_, i) => ({key: length - i, [length - i]: parsed[length - i]}));
// Log a copy of the result.
console.log(JSON.parse(JSON.stringify(result)));
// Sort ascending:
result.sort((a,b) => a.key - b.key);
// Log a copy of the sorted result.
console.log(JSON.parse(JSON.stringify(result)));
// Sort descending:
result.sort((a,b) => b.key - a.key);
// log the sorted array
console.log(result);
If you really want to rely on key orders, you can (of course), but using an array is slightly cleverer and gives no chance to have something which is not ordered as expected, unless (of course) the sorting algorithm is wrong or fails for some reason (like if key is undefined or null or not numeric in the above case).
As a final note, I'm aware that the question is about sorting an object, but because of the above reasons, I think the correct answer is just to DON'T use an object at all in that scenario specifically.
I'm working with a buffer array that I am periodically checking. When I am mapping through the elements, I would like access the element using the shift method, this way I would get the next element in the array and would also remove it. Is there a way to do this in a map? Thank you!
I currently have a naive solution, which is prone to race conditions.
if (timestep) {
bufferArray.map((mvt) =>{
console.log(mvt)
});
bufferArray = [];
}
As I would like to go through the elements of the array one by one and remove the current element from the array. For this reason a simple and great solution is to use a while loop with the shift method. For example:
let arr = [0,1,2,3,4,5];
while (arr.length)
{
let current = arr.shift()
// do something with current
}
I have an object that I would like to push an indeterminate amount of other objects to, using a loop. To keep it organized, I'd like to dynamically name the keys based on them amount of times the loop runs. I have the following:
let formsJson = {};
let counter = 1;
//savedForms are where the objects that I want to push reside
savedForms.forEach( form => {
formsJson['form'+counter] = JSON.parse(form.firstDataBit_json);
//This is where I'm having trouble
counter = counter + 1;
});
I can push the first bit of data fine, and name the key dynamically as well. But I need to push 2 more objects to this same dynamic key, and that's where I'm having trouble. If I try the obvious and do:
formsJson['form'+counter].push(JSON.parse(form.secondDataBit_JSON));
I don't get any output. Is there a way to accomplish this?
forEach() gives you access to the index already. No need to create the counter variable. Example usage. I would definitely recommend using a simple index, and not using the 'form'+counter key.
In your example, it's not clear to me that the value being assigned in the forEach loop is an array. So it's unclear if you can push to any given element in that. But generally that syntax should
Personally, I would prefer to have a function that outputs the entire value of the element. That would provide better encapsulation, testability, and help enforce default values. Something like:
function createItem(param1) {
let item = [];
item.push(param1.someElement);
if (foo) {
item.push(...);
} else {
item.push(...);
}
return item;
}
formsJson['form'+counter] = createItem( JSON.parse(form) )
So you're making formsJson['form'+counter] a by assigning the JSON parse, not an array as you want. Try this:
formsJson['form'+counter] = [];
formsJson['form'+counter].push(JSON.parse(form.firstDataBit_json));
formsJson['form'+counter].push(JSON.parse(form.secondDataBit_JSON));
Maybe you want to figure out something like this
savedforms.forEach((form, index) =>
formsJson[`form${index + 1}`] = [ JSON.parse(form.secondDataBit_JSON)])
Now you can push on the item
formsJson[`form${index + 1}`].push(JSON.parse(form.secondDataBit_JSON));`
Also here you'll save operation on incrementing it will be automaticly
I'm trying to understand how to iterate through this simple array.
var data = [{"blahh":"hi","blah2":"333","third":"920","fourth":"800"}];
What I am trying to accomplish is, appending an object that is the sum of certain keys (the 'third' and 'fourth')...resulting data being this:
var data = [{"blahh":"hi","blah2":"333","third":"920","fourth":"800", "sum": "1720"}];
I imagine 'lodash' library is capable of neatly accomplishing this. I just can't figure out how to pull that off. I know this is a newbie question but perhaps answering it may helps some soul better understand lodash.
As mentioned - you don't need lodash for this. You're looking at the map function to iterate over an array and return a new array (in this case an array of objects returning a new array with objects that have a sum property) and reduce to iterate over all desired keys and sum their values. For example:
//If you want to treat numbers as numbers then use numbers.
//Some answers here are coercing strings with + - however this will result in NaN on non coerceable strings -ie 'hello',
//which will cause unexpected errors for you later (and typeof NaN is number)
var data = [{"blahh":"hi","blah2":333,"third":920,"fourth":800}];
function returnNewArrayWithSums(keys, array) {
return array.map(obj => {
obj.sum = keys.reduce((sum, key) => typeof obj[key] === 'number' ? obj[key] + sum : sum, 0);
return obj;
});
}
returnNewArrayWithSums(['third', 'fourth'], data);
edited to add - this answer is to give you a use case w/ map/reduce - ideally you wouldn't have to specify numeric keys and make this function more general for any arrays that have objects with k/v pairs that are nums that you want to sum
No need for a library to do this ... the code will likely be more complicated looking than using native methods
data.forEach(item){
item.sum = (+item.third || 0) + (+item.fourth || 0);
});
You have an array of one object - which I dont think you are trying to do. Arrays do not have a key:value pair in them (well actually they do in JavaScript but ignore that). They are an indexed list of values. You probably want to do something like this:
// notice im not putting the integer values in quotes
var data = {'blah':'hi', 'blah2':333, 'third':920, 'fourth':800 };
data.sum = data.third + data.fourth;
That will add a 'sum' field to your object with the value of the sum of third and fourth. Is this what you are trying to do?
I'm trying to make a little damage calculator for the game Diablo 3 (I know, I know).
Basically the idea is that it has a "before" and "after" array of values that represent items for your character. The "after" array should duplicate the "before" array when that's updated. However, changes to the "after" array should not update the "before" array.
Each array then displays a DPS (more of this is better) total, and it shows you the difference between the two. The idea is then it makes for easy comparison of two items when using the in-game auction house.
I have the first bit set up - the "before" array is working great. However I'm at a loss as to how to create the "after" array, and I'm wondering if I've made this a different magnitude of complexity. Should I be using two view models, replicating it in jQuery, or using the mapping plugin? I can't quite find anything that's exactly what I'm after, the UI requirements especially seem a bit of a sticking point
Fiddle of where I'm up to: http://jsfiddle.net/kimadactyl/GuMuY/8/
Here's a solution that should get you started. I refactored your HeroItem to take a config object and an optional linked Hero.
I am assuming for the moment the array is fixed length. I create the after array from the items array by mapping it to a new HeroItem, using jquery extend to do a deep copy.
When a link is passed in the HeroItem will subscribe to changes on it's observables and update one-way only as specified.
function HeroItem(config, link) {
var self = this, prop;
self.item = config.item;
self.int = ko.observable(config.int);
self.ias = ko.observable(config.ias);
self.critdmg = ko.observable(config.critdmg);
self.critpc = ko.observable(config.critpc);
self.min = ko.observable(config.min);
self.max = ko.observable(config.max);
if (link) {
for (prop in link) {
if (link.hasOwnProperty(prop) && ko.isObservable(link[prop])) {
console.log("subscribing " + prop);
link[prop].subscribe((function(p) {
return function (newValue) {
console.log("updating " + p+ " to " + newValue);
self[p](newValue);
}
})(prop));
}
}
}
}
self.after = ko.observableArray(ko.utils.arrayMap(self.items(), function(i) {
return new HeroItem($.extend({}, ko.toJS(i)), i);
}));
http://jsfiddle.net/madcapnmckay/2MNFn/1/
No custom bindings needed, it just uses the subscription capabilities all KO observables have. If you want to extend this to cope with dynamic length arrays simple subscribe to the items array and cleanup the after array accordingly.
Hope this helps.