I have this code here http://jsfiddle.net/so0rL8kj/3/
and I'm having trouble implementing a check of does input already exist in object array.
I've tried looping over json.parse(urls) something like this
if (this.url == id) {
console.log("found: " + JSON.stringify(this));
$(".order").append("<li>" + id + " ... already exists in your list.</li>");
return false;
}
But that did not stop the code from executing the localstorage.setitem save. I also tried to save as an array and then using inArray() but had no results with this functionality either.
How do I add a check to stop duplicates from user input for localstorage?
edit: working fiddle http://jsfiddle.net/so0rL8kj/4/
You can't use $.inArray() to compare a string to an array of objects.
Array would look something like:
[{"url":"someVal"},{"url":"Anotherval"}]
All $.inArray() will do is look at each object, and will never find a match since you are looking for the value of an object property in each element of the array
You can use a for loop to iterate the array and compare each url property to the string or use various array methods like Array.prototype.filter()
var alreadyExists = arrayCheck.filter(function(item){
return id ==== item.url
}).length;
This filters the array to objects that match the url to id and if it has no length there is no match
Related
I'm using a ng-change directive to get an object that change. When i get it i have to check if exists in another array of objects, and if it does i have to delete from it.
what can i do? i tried with indexOf but it didn't work.
//#Param ObjectItem: change object from UI using ng-change
$scope.itemValue = function (ObjectItem) {
//collection of required items
var requiredItem = dataPublicationService.getRequired();
//check if item exist in collection. DIDN'T WORK!
if(requiredItem.indexOf(publi) !== -1){
//get found index
var idx = requiredItem.indexOf(publi);
//delete founded item.
requiredItem.splice(idx, 1);
}
};
What other solution can i implement?
The indexOf function doesn't delete from an array, it just finds the index of the given object if found. You might consider filtering the array and testing for a match, rather than relying on indexOf to find a matching object.
Once you find your record, you need to actually alter the array using something like Array#splice.
I am dealing with an array that I want to delete an object from and return the new length of the array. For all other numbers, it works - but for one item, it does not. Not sure how to fix it so that the array length is 0 after the only object is deleted. My code is below:
Here's an example where I had one object in the 'player' array:
function deletecamera(id){
alert('before the splice, player length =' + player.length); //returns 1
delete player.splice((id),1);
i=0;
for (i=0;i<player.length;i++){
player.id=i;
}
alert('after reassigning, player length =' + player.length); // still returns 1?!
refreshlist();
}
the delete keyword doesn't remove the object from the array, it sets its value to undefined, so the size of the array stay the same.
See example here: http://jsfiddle.net/up5XX/
If you want to remove the first element from the array player using .splice, you can do this:
player.splice(0, 1);
yeah, thinking a bit more about this, I bet it will work if you change this line:
delete player.splice((id),1);
to
player.splice((id),1);
some weird codes there.
An array in JS is an object that can hold multiple [elements]. But just like with any other JS object you can add more members to it by just saying myArrayName.someMemberName = something. This will not be 'in' the array as if it was an element. This is even the JS poor mans way for an 'associative array’. This is what you are doing now with the .id = ...
You need to change
player.id = i;
into something like
player[i].id = i;
(or something like it. Don't know what the goal is there. I guess you want to reorder all Id's after deleting one in between.)
futhermore ... change the splice line to just this:
player.splice(id,1);
and remove the extra line with just:
i=0;
But I now realise these all are tips but no solution to your problem.
Can you please add
alert('trying to remove id ' + id);
and confirm that you do at least once try to delete id 0 ?
I'm working on JavaScript and I have this JSON object:
var obj ={"name" : "objName",
"dynamicList" :[]};
and then I add some items to my list like this:
obj.dynamicList["someStringID"] = {"watever"};
It's important that I use a string as indexer for each item on my list (i didn't know this could be done until recently).
My only problem now is that whenever I ask for obj.dynamicList.lenght I get 0, unles I manually set the proper number... I was wondering if there's a better way to add items to my list?
Thanks!!
In Javascript, string index is not really an index. It's actually an attribute of the array object. You could set and get the value with the string index, but it's actually an empty array with some attributes. Not only .length, but also .sort(), .splice(), and other array function would not work. If there is a need to use array functions, I would use number as an index to make it a real item in the array.
If you have to use the string as an index, you couldn't rely on .length function. If there is no need to support IE prior to version 9, the Object.keys as suggested by #strimp099 should work. or you may have to create function to count the number of attributes for example:
function len(obj) {
var attrCount = 0;
for(var k in obj) {
attrCount++;
}
return attrCount;
}
and then call
len(obj.dynamicList);
Use the following the find the length of dynamicList object:
Object.keys(obj.dynamicList).length
To do this "the right way," you will have to make obj.dynamicList an object instead of an array; use {} instead of [] to set the initial value.
How to efficiently count the number of keys/properties of an object in JavaScript?
dynamiclist is an object, the length is not the length property you expect from an array.
I have a json object array. I want to search the array and for each object, create a list of 'services' that is a comma-seperated list of all the keys which have a value of "yes".
The list of json objects with the services list is then displayed in html using jquery's each.
Its a large json file so I want to do it as efficiently as possible.
I already have the object's properties being accessed through jQuery's each (ie, obj.name)
-- so I think it should be possible to filter the services listed for each object using
jQuery's filter, and then display the key if the value is yes.
But it seems like a more efficient option would probably be to create a new javascript array, join the services with a value of yes and then add that variable to the html being
appended.
Im not sure which would be faster and so far havent been very successful at either... so any advice and examples would be very helpful.
Here's what the json array looks like:
[
{"name":"name1",
"service1":"y",
"service2":"y",
"service3":"n",
},
{"name":"name2",
"service1":"n",
"service2":"y",
"service3":"n",
},
];
If you just want to filter the array then use grep.
grep - Finds the elements of an array which satisfy a filter function. The original array is not affected.
http://api.jquery.com/jQuery.grep/
First off, delete trailing commas. Internet Explorer gets really, really confused by them. Anyway, I assume you don't want to "search" the array when you say "for each value"; you want to iterate through the array and parse it into a more usable list. The first method I'd suggest is just passing what you want as the array you desire, but if that's not an option, what you're looking for is some variant of this, which should be fairly efficient (jsFiddle example):
var json = [
{"name":"name1", "service1":"y", "service2":"y", "service3":"n"},
{"name":"name2", "service1":"n", "service2":"y", "service3":"n"}
];
var parsed = {};
for (var i = 0, iLen = json.length; i < iLen; i++) {
// Assuming all we need are the name and a list
var name;
var list = [];
for (var key in json[i]) {
var value = json[i][key];
// We need to hold on to the name or any services with value "y"
if (key === "name") {
name = value;
} else if (value === "y") {
list.push(key);
}
}
// Add them to the parsed array however you'd like
// I'm assuming you want to just list them in plain text
parsed[name] = list.join(", ");
}
// List them on the web page
for (var key in parsed) {
document.write(key + ": " + parsed[key] + "<br>");
}
That way you wind up with a display to the visitor of the services available and still keep an array around for further use if necessary.
jQuery.inArray() Search for a specified value within an array and return its index (or -1 if not found).
http://api.jquery.com/jQuery.inArray/
Or
http://api.jquery.com/jQuery.each/
I have some items I am storing in an element that get added at various times like this:
document.getElementById('rout_markers').value = str;
I am not too good with JavaScript, but as I understand it, the values get stored as an array, correct?
What I need to do is to be able to remove all the elements or to be able to remove the last element that was added.
How can I do that?
Thanks!
If you're assigning str to an element then there are no arrays involved here - you'll be overwriting each previously-assigned value with the latest and thereby storing only the latest value.
You could use an array but you'd have to know the location of each item in the array, so if you wanted to assign or nullify a specific element in your array, you'd have to a have a record of where it was - although you could get around that it with a multi-dimensioned array, where the first element at each index is the name of the property, and the second element at each index is that value of the property.
If you want to store multiple properties in a field in order to retrieve them all later, there are two simple ways of doing this.
Consider using either a field for every property.
If you do this then I'd suggest using a naming convention for the fields so that you can more easily assign the property.
Concatenating a string to form a collection of key-value pairs, very much like a query-string.
In the example you gave, this would mean storing something like:
var keyVals = 'route_markers' + '=' + str + '&';
document.getElementById('myHiddenProperties').value = keyVals;
When you want to assign another property to this string you do something like this:
keyVals = document.getElementById('myHiddenProperties').value;
keyVals += 'new_property' + '=' + myNewValue + '&';
document.getElementById('myHiddenProperties').value = keyVals;
In this way, if you want to remove a specific key-value pair, you split the stored value like this
var arrKeyVals = document.getElementById('myHiddenProperties').value.split('&');
You then have an array of key-value pairs.
If you want to retrieve a value from this array, or blank one of the values then loop through this array, splitting each into its key and value, like this:
for (var i = 0; i < arrKeyVals.length; i++) {
var keyVal = arrKeyVals[i].split('=');
var key = keyVal[0];
var val = keyVal[1];
if (key == name_of_key_sought) {
val = ''; //assign an empty string to this property to forget about it
}
}
I am not too good with JavaScript, but as I understand it, the values get stored as an array, correct?
No, the value property of certain HTML elements is just a string value. (And it only exists on certain elements, like input.) Assigning a new value to value will overwrite the previous value, not store it in an array.
What I need to do is to be able to remove all the elements or to be able to remove the last element that was added.
This part of the question sort of goes away because of the answer to the first part, but you can clear the value property by assigning an empty string to it.
If by any chance you mean remove/hide the element itself (the text box) then you can have such code:
document.getElementById('rout_markers').style.display = 'none';
Otherwise the other answers here cover it all nicely.