How to store integer indexed data in Javascript? - javascript

I'm coming from working in PHP for many years and having trouble wrapping my head around creating some more complicated data structures in JS for objects that are integer IDed. I need to build an object the stores these simpler objects hierarchically keyed on their integer ids. So if I have the following objectes each of which has a unique integer id:
section, element, item, entry
in php I would do something like
$arr[$section_id][$element_id][$item_id][$entry_id] = $entry;
In javascript this does not work. I know I could technically wrap those IDs in quotes to force it but that seems like a bad idea. Similarly I could create an object and use the quoted integer approach but again that seems hacky.
Right now I am storing the data in regular integer indexed arrays and then using caolan's async detect to look up a particular member by ID. This works but seems extremely messy compared to the php equivalent. I'm hoping there's a cleaner way to do this in JS.
TIA!

since javascript cannot save an array with string index, i use these :
var namespace = function(name, separator, container){
var ns = name.split(separator || '.')
, o = container || window
, i = 0;
while (i++ < ns.length) o = o[ns[i - 1]] = o[ns[i - 1]] || {};
return o;
}
namespace(arr + '.' + section_id + '.' + element_id + '.' + item_id + '.' + entry_id) = entry;
// ex : namespace('arr.1.3.2.6') will product arr.1.3.2.6 object

This is a little ugly, but it will get you pretty close to what you want.
You can add a method to the JavaScript Array class like so:
Array.prototype.g = function(index) {
if (this[index] == undefined) {
this[index] = [];
}
return this[index];
}
Then, to set something you would do this:
var test = [];
test.g(5).g(7)[5] = 1;
Unfortunately, for the last entry you'd have to remember to use the regular notation to set the value.
You would retrieve it like you expect:
test[5][7][5]; //1
Obviously I just pulled g out of thin air, you could come up with your own function name.
Disclaimer: People tend to frown on extending the built in types using the prototype chain, but as far as I know most major frameworks no longer do this so unless you or some third party JS is using the same name to extend Array somewhere else you should be fine.

Related

Dynamically create a TW object in IBM BPM

I am using IBM BPM 8.6
I have an input string as follows:
"\"RECORD_CONTACT\":\"Maram\" , \"DRUG\":\"Panadol\"
In a script on server side, I want to dynamically create a business object like this:
tw.local.recordContact = Maram;
tw.local.drug = Panadol;
How can I dynamically create the business object?
There are a few problems with your request. The first is that you are not creating a business object, you are creating variables. In IBM BPM the variables have to be declared at design time or you will get an error, so invoking attempting to call something like -
tw.local.myVariable = 'Bob';
Will throw an exception if tw.local.myVariable has not been declared. Base on your other question you asked here (link), I'm going to assume you actually have an ANY variable declared called "return" so that
tw.local.return.myVariable = 'Bob'
will work. Given that I based on Sven's answer I think something like the following will work (you will need to validate)
var str = "\"RECORD_CONTACT\":\"Maram\" , \"DRUG\":\"Panadol\"";
var jsonStr = "{" + str.replace(/\\\"/g,'\"') + "}";
var tempValue = JSON.parse(jsonStr);
var keyArray = Object.keys(tempValue);
var valueArray = Object.values(tempValue);
for(var keyCount=0; keyCount<keyArray.length; keyCount++{
var evalString = "tw.local.return."+keyArray[keyCount]+"="+valueArray[keyCount];
eval(evalString);
}
I'll note that doing this is a very bad idea as it would be very brittle code and that using eval() in this manner opens you up to all sorts of possible exploits. It will also fail badly if the value for one of the keys is not a simple type.
-Andrew Paier
One should know what you are going to do with dynamically created Business Objects (BO) to answer you better. Like a very generic way would be - creating JSON object instead of BO.
But if you want to stick with BO then this is only possible when you know all the BO structure (schema) beforehand during design time.
var str = "\"RECORD_CONTACT\":\"Maram\" , \"DRUG\":\"Panadol\"";
vat objArray = str.split("reg ex to split each object string")
foreach (obj in objArray ){
if(obj.indexOf( "RECORD_CONTACT")!=-1)
tw.local.recordContact = new tw.object.RECORD_CONTACT();
//below goes code get value of each attribute of BPM from string
}
else if(obj.indexOf( "DRUG")!=-1){
//similar code to create BO DRUG
}
Don't forget to create BO before using those :)

Creating and populating a json object

I need to construct and populate a json object with values coming from a method.
A bit of background to this: I'm searching pdf documents with a designated keyword and if I find any match, for each match I need to save:
-the whole sentence where the match is found
-the search term (defined elsewhere: the search term is always the same, so it's really redundant here, but I might need it in the json object that's why I'm including it)
-the result (which is the index where the search term is found in a whole sentence and it should be an integer)
So, here is some code.
I have this function call inside a loop (the loops goes through the pages and then there is a second loop that goes through the text):
for(var i = 0; i < items.length; i++){
lineWithResult = searchPdf(block.str);
if(lineWithResult != null){
console.log(lineWithResult + " wordCounter is " + wordCounter);
}
}
and the function itself:
function searchPdf(toSearch){
var result = toSearch.toLowerCase().indexOf(searchTerm);
if(result >=0){//if match is found
wordCounter++;
//console.log("toSearch " + toSearch + " result is " + result + " wordCounter " + wordCounter);
return toSearch;
}
else{//if match not found
return null;
}
}
SO I need to construct a json object that at each iteration takes in the parameters discussed above:
So, what would be the best way - I'm a bit rusty with json?
I think I would start by creating an empty object like so (if that's even a valid definition):
var searchResult = {"Line" : "", "SearchTerm" : "", "Result" : ""}
If the above is right, where do I define the object and how do I fill it up with the relevant values? Bear in mind that there will be a lot of Lines, one search term and a lot of Results because the documents (a pdf) which I will use are quite big and can returns lots of matches
thanks
With saying something like that:
var searchResult = {"Line" : "", "SearchTerm" : "", "Result" : ""}
You have already defined the object. JavaScript (at this point) is prototypical, not a "class" based language. JSON in JavaScript is not much more than just a plain JavaScript object. If you want to to create multiple objects of that kind, you have various options. I recommend you to read about JS Object creational patterns.
Here is a good link.
That being said, you could do something like that:
// ... maybe inside a function
return {
line: myLineValue,
searchTerm: mySearchtermValue,
result: myResult
}
There is no need to init something with empty values; you just create the object with the curly brackets.
Hope this makes sense to you; if not, let me know in the comments, and I will try to improve my answer. :-)

example of javascript's eval not being evil?

I read some stackOverflow questions and answers more then ten times per day, and... it looks its first time i feel its okey to post something, as i didnt find accurate enought answer.
Im writing some code in nodeJS. Its web interface for big softswitch based on custom asterisk, where in one place i need to get data from post message from website.
The problem is, that that post message containts numerous info named in fashion:
peer1
peer2
peer3
peer4 etc
Instead of dealing with every single one, i did a loop:
var array = [];
var i = 0;
while (typeof eval("req.body.peer" + i) !== 'undefined' && eval("req.body.peer" + i) !== '') {
console.log('petla wisielca');
//console.log(eval("req.body.peer" + i));
array.push(eval('req.body.peer' + i));
i++;
}
Number filled inputs (actually its html select) is variable.
After creating that array, I deal with rest of things (write peers to file etc) in traditional, non-eval loops.
Am i missing something here, or it's proper way of dealing with such situation?
Thanks in advance!
EDIT:
Looks like i had some kind brain malfunction :).
Solution is very easy,
as kyle cleared it out, to access object variables and for example iterate, all is needed is to use [].
Solution:
var array = []
var i = 0
while (req.body['peer' + i]) {
array.push(req.body['peer' + i])
i++
}
Thanks once more Kyle.
JavaScript objects can be accessed like they're associative arrays:
var array = []
var i = 0
while (req.body['peer' + i]) {
array.push(req.body['peer' + i])
i++
}
Use of eval is ever evitable, i wrote a plugin that make some dynamic calls of functions, you can check how you can access the object without using eval:
https://github.com/HaSuKrOnOs/jquery-dynFn

Dynamically making a Javascript array from loop

I know there are a lot of questions about this, but I can't find the solution to my problem and have been on it for a while now. I have two sets of input fields with the same name, one for product codes, and one for product names. These input fields can be taken away and added to the DOM by the user so there can be multiple:
Here is what I have so far, although this saves it so there all the codes are in one array, and all the names in another:
var updatedContent = [];
var varCode = {};
var varName = {};
$('.productVariationWrap.edit input[name="varVariationCode[]"]')
.each(function(i, vali){
varCode[i] = $(this).val();
});
$('.productVariationWrap.edit input[name="varVariationName[]"]')
.each(function(i1, vali1){
varName[i1] = $(this).val();
});
updatedContent.push(varCode);
updatedContent.push(varName);
I am trying to get it so the name and code go into the same array. i.e. the code is the key of the K = V pair?
Basically so I can loop through a final array and have the code and associated name easily accessible.
I can do this in PHP quite easily but no luck in javascript.
EDIT
I want the array to look like:
[
[code1, name1],
[code2, name2],
[code3, name3]
];
So after I can do a loop and for each of the arrays inside the master array, I can do something with the key (code1 for example) and the associated value (name1 for example). Does this make sense? Its kind of like a multi-dimensional array, although some people may argue against the validity of that statement when it comes to Javascript.
I think it's better for you to create an object that way you can access the key/value pairs later without having to loop if you don't want to:
var $codes = $('.productVariationWrap.edit input[name="varVariationCode[]"]'),
$names = $('.productVariationWrap.edit input[name="varVariationName[]"]'),
updatedContent = {};
for (var i = 0, il = $codes.length; i < il; i++) {
updatedContent[$codes.get(i).value] = $names.get(i).value;
}
Now for example, updatedContent.code1 == name1, and you can loop through the object if you want:
for (var k in updatedContent) {
// k == code
// updatedContent[k] == name
}
Using two loops is probably not optimal. It would be better to use a single loop that collected all the items, whether code or name, and then assembled them together.
Another issue: your selectors look a little funny to me. You said that there can be multiple of these controls in the page, but it is not correct for controls to have duplicate names unless they are mutually exclusive radio buttons/checkboxes--unless each pair of inputs is inside its own ancestor <form>? More detail on this would help me provide a better answer.
And a note: in your code you instantiated the varCode and varName variables as objects {}, but then use them like arrays []. Is that what you intended? When I first answered you, i was distracted by the "final output should look like this array" and missed that you wanted key = value pairs in an object. If you really meant what you said about the final result being nested arrays, then, the smallest modification you could make to your code to make it work as is would look like this:
var updatedContent = [];
$('.productVariationWrap.edit input[name="varVariationCode[]"]')
.each(function(i, vali){
updatedContent[i] = [$(this).val()]; //make it an array
});
$('.productVariationWrap.edit input[name="varVariationName[]"]')
.each(function(i1, vali1){
updatedContent[i1].push($(this).val()); //push 2nd value into the array
});
But since you wanted your Code to be unique indexes into the Name values, then we need to use an object instead of an array, with the Code the key the the Name the value:
var updatedContent = {},
w = $('.productVariationWrap.edit'),
codes = w.find('input[name="varVariationCode[]"]'),
names = w.find('input[name="varVariationName[]"]');
for (var i = codes.length - 1; i >= 0; i -= 1) {
updatedContent[codes.get(i).val()] = names.get(i).val();
});
And please note that this will produce an object, and the notation will look like this:
{
'code1': 'name1',
'code2': 'name2',
'code3': 'name3'
};
Now you can use the updatedContent object like so:
var code;
for (code in updatedContent) {
console.log(code, updatedContent[code]); //each code and name pair
}
Last of all, it seems a little brittle to rely on the Code and Name inputs to be returned in the separate jQuery objects in the same order. Some way to be sure you are correlating the right Code with the right Name seems important to me--even if the way you're doing it now works correctly, who's to say a future revision to the page layout wouldn't break something? I simply prefer explicit correlation instead of relying on page element order, but you may not feel the need for such surety.
I don't like the way to solve it with two loops
var updatedContent = []
$('.productVariationWrap.edit').each(function(i, vali){
var $this = $(this)
, tuple = [$this.find('input[name="varVariationCode[]"]').val()
, $this.find('input[name="varVariationName[]"]').val()]
updatedContent.push(tuple)
});

Are there any JSON pretty-printers that take extra care to be concise?

I'd like a JSON pretty printer that would recognize when an array or object fits on one line and just do that. Example:
{
"fits": ["JSON", "pretty", "printer"],
"longer": [
"???????????????????????????????????????????????????",
"???????????????????????????????????????????????????",
"???????????????????????????????????????????????????",
"???????????????????????????????????????????????????",
"???????????????????????????????????????????????????"
]
}
Is there a standalone library like this? If not, how would I go about writing one?
I'm most interested in a JavaScript implementation.
I don't know about any such concise JSON printer, but it shouldn't be hard to make your own if you want to:
You can use the for(property in object) to iterate over the properties of a given object.
Depending on use case, you might want to filter with hasOwnProperty.
You can determine if an reference points to an object, array, string or number with typeof
Have your pretty printer function receive the initial indentation offset and the object to be printed. This might be enough to decide if you should inline each property or not.
I'm not sure this "greedy" strategy is always "optimal" - perhaps it might be better to do something in multiple lines now to be able to inline later. I wouldn't worry with this at first though.
Since JSON is primarily a data transport format, I assume that you mean viewing raw JSON in the browser? If so, then there are a few options:
JSON Lint - Checks and reformats JSON
A pure JS version of the above
JSONView for Chrome
Safari JSON Formatter
You should be able to dig into the source of the last three if you require further customization. I'd start with iterating through the value.length property where value is/are the array element(s) to see if you can limit your output to a single line.
Use a replacer function to compare the total number of characters in each key/value pair to a fixed length. Here is a simple example:
function replacer(key, value)
{
var key_arr = [];
var value_arr = [];
var i = 0;
for (_ in value)
{
key_arr.push(_);
value_arr.push(value[_]);
}
for(;i < value_arr.length;i++)
{
if (key_arr[i].length + value_arr[i].length < 80)
{
console.log(key_arr[i] + ":" + "\t" + value_arr[i])
}
else
{
console.log(key_arr[i] + ":" + "\n" + value_arr[i])
}
}
}
Usage:
var json;
json = {"foo":"1","bar":"2"},
JSON.stringify(json, replacer, 4);
json = {"foo":"12345678901234567890123456789012345678901234567890123456789012345678901234567890","bar":"2"};
JSON.stringify(json, replacer, 4);

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