I've been trying at this for hours now and I thought it would be really simple;
Using javascript I basically want to iterate through an array, get the current value of the index and then unset this value from the array. I've found splice() is supposed to work for this however I don't seem to be able to empty the array, there is always one value left on the arrary
var filtered = array("up", "down", "left");
function resetTags(){
var length = filtered.length;
for(i=0; i <= length; i++){
filtered.splice(i,1);
}
}
EDIT::
I'll try to explain in a bit more detail:
I'm basically trying to keep track of a listed of selected class values which are obtained
from when an item is clicked:
var filtered = array();
jQuery("li a").click(function () {
tag = jQuery(this).text();
addFiltered(tag);
});
function addFiltered(param){
var inArray = jQuery.inArray(param,filtered);
if(inArray > -1){
//param is in array, so we want to remove it from the filtered array
filtered.splice(index, 1);
});
}else{
//param isn't in array, so we want to add it to the array
filtered.splice(0, 0, param);
});
}
}
If you want to empty the array, set it to be an empty array directly:
filtered = [];
If you want to use the values before emptying the array, simply iterate before that without removing values and clear it when you are done.
What do you stand to gain by messing with convoluted solutions?
the array was defined incorrectly. That is why the code didn't excute
var filtered = ["up", "down", "left"];
function resetTags(){
var length = filtered.length;
for(i=0; i <= length; i++){
filtered.splice(i,1);
}
}
To remove items one by one:
var a = [1,2,3,4,5];
while (a.length > 0 ) {
a.splice(0,1);
}
http://jsfiddle.net/89hkH/
Well, you're incrementing. Have you tried decrementing?
var filtered = new Array("up", "down", "left");
function resetTags(){
var length = filtered.length;
for(i = length; i >= 0; i--){
filtered.splice(i,1);
}
}
This should make sure the final element is spliced.
I basically want to iterate through an array, get the current value
of the index and then unset this value from the array.
for(i=0; i <= length; i++){
filtered.splice(i,1);
}
I don't think you are clearly defining (or perhaps don't know), what you're trying to do.
Are you trying to write a pop(n) method such that:
var a = [1,2,3,4]
var result = pop(3, a)
result == [ 1, 2, 4]
Or are you just trying to walk an array and get the first element off every time? If so, you're doing it wrong. That's just a shift()
var filtered = ["up", "down", "left"]
for(i = 0 ; i<= filtered.length; i++)
{
alert(filtered);
filtered.shift();
alert(filtered);
}
Related
What I am trying to do is:
set an array value (list) to another array (options).
If the user's input (searchVal) matches with a list value it will delete options, push this match, and then will keep pushing the next matches without deleting options again.
So according to the code below, if searchVal was "whatever", options should return: ["whatever", "whatevEver1"] but, instead, it returns: ["whatever", "WhatEver1", "whatttever", "whatever", "whatevEver1"]
Relevant code:
var list = ["whatever", "WhatEver1", "whatttever"];
var clear = 0;
var options = [];
for (var i=0 ; i < list.length ; i++)
{
options.push([list[i]]);
}
var searchVal = window.prompt(" ");
for (var i=0 ; i < list.length ; i++)
{
if (list[i].toLowerCase().includes(searchVal.toLowerCase())) {
if (clear == 0) {
options.length = 0;
}
options.push([list[i]]);
}
clear++;
}
return options;
Js arrays are pass-by-reference. In order to make independent copy of array you need to use:
let options = JSON.parse(JSON.stringify(list));
I didnt try to implement this to your problem cause im too lazy but i think it might work.
Seen this question a lot, but cannot find something that's what i'm looking for.
onClick I push an item to an array I have, however, if there's 3 items in my array I don't want to be able to push items anymore.
var selectedData = [];
I set my empty variable.
var index = selectedData.indexOf(3);
I then get the index of my array which is 3
if (index > 3) {
selectedData.splice(index, 1);
}
Then within my if statement I say, if my index which is 3, is bigger then 3, then splice at index and remove one.
selectedData.push(TheThing);
I then push TheThing to my array if the if statement above isn't true.
However, I have a variable var arrayLength = selectedData.length; that grabs the length, and when I console log it, it starts at 0 and splices items anything after 4. Not 3.
Any idea what i've done wrong or misunderstood?
Thanks
More full example of my code
var selectedData = [];
myElement.on('click', function() {
var index = selectedData.indexOf(3);
if (index > 3) {
selectedData.splice(index, 1);
}
var arrayLength = selectedData.length;
console.log(arrayLength, 'the length');
});
So in short, onClick check my array and remove anything after the third that gets added into my array.
Do you want this to behave as a stack or a queue?
So your code here:
var index = selectedData.indexOf(3);
Is not grabbing the 3rd index - its grabbing the first index where it sees 3, or -1 if it doesn't. Replace your if statement with,
if (selectedData.length > 3) {
selectedData.pop() // removes last element (stack)
// or
selectedData = selectedData.slice(1) //remove first element (queue)
}
I think you need to try var arrayLength = selectedData.length -1;
You start at 0 like a normal array, but don't you start with an empty array?
Plus when you use .length, it returns the true count of the array or collection not a 0 index.
`
you can override push() method of your array like this:
var a = [];
a.push = function(){}
or like this
a.push = function (newEl){
if(this.length <3){
Array.prototype.push.call(this, newEl)
}
}
This is not complete example because push() can take many arguments and you should to handle this case too
var index = selectedData.indexOf(3); simply give you the index of the element of the array that has value 3
Example
selectedData = [ 0, 3 , 2];
alert( selectedData.indexOf( 3 ) ); // this will alert "1" that is the index of the element with value "3"
you can use this scenario
var selectedData = [];
myElement.on('click', function() {
//if selectedData length is less than 3, push items
});
This could work.
myElement.on('click', function() {
if(selectedData.length > 3){
selectedData = selectedData.splice(0, 3);
}
console.log(selectedData.length, 'the length');
});
I have an object and an array of categories that should be kept in the object. This snip https://jsfiddle.net/h10rkb6s/2/ ( see log ) works but I cant seems to shake the idea that it is to complicated for a simple search and keep task.
var thz_icon_source = {"Spinners":["spinnericon1","spinnericon2"],"Awesome":["awesomeicon1","awesomeicon2"],"Others":["othericon1","othericon2"]};
var $categories = '["Spinners","Awesome"]';
var $CatsArray = JSON.parse($categories);
var groups = [];
for(var k in thz_icon_source) groups.push(k);
$.each($CatsArray,function(i,keep){
var index = groups.indexOf(keep);
if (index !== -1) {
groups.splice(index, 1);
}
});
for (var i = 0; i < groups.length; i++) {
delete thz_icon_source[groups[i]];
}
I tried with
$.each(thz_icon_source,function(category,icons){
$.each($CatsArray,function(i,keep){
var index = category.indexOf(keep);
if (index !== -1) {
delete thz_icon_source[category];
}
});
});
but this works only if 1 item is inside my search array.
Any help is appreciated.
There's no need to iterate over $CatsArray to find out which ones should be deleted. You will need to iterate over the keys of the object, and find out for each of them whether it should be deleted, to filter by that.
Leaving the top 3 lines of your script intact, you could simplify to
var keysToDelete = Object.keys(thz_icon_source).filter(function(groupName) {
return $CatsArray.indexOf(groupName) == -1;
});
($.grep would be the jQuery-ism for the filter method, if you are into that).
But assuming we don't even need those groups in an array, you could simply do
for (var groupName in thz_icon_source)
if ($CatsArray.indexOf(groupName) == -1)
delete thz_icon_source[groupName];
However, instead of deleting items from that object, I'd recommend to create a new object with only those that you want to keep. It's much easier to use:
var kept = {};
for (var i=0; i<$CatsArray.length; i++)
kept[$CatsArray[i]] = thz_icon_source[$CatsArray[i]];
I have an array containing a list of tags and count.
tags_array[0] = tags;
tags_array[1] = tags_count;
I need to sort the arrays base on the count so that I can pick out the top few tags.
Sort one, while storing the sort comparisons. Then sort the other using those results:
var res = [];
tags_count.sort( function( a, b ){ return res.push( a=a-b ), a; } );
tags.sort( function(){ return res.shift(); } );
Supposing tags and tags_count are 2 arrays of same length, I would first build a proper array of objects :
var array = [];
for (var i=0; i<tags_count.length; i++) {
array.push({tag:tags[i], count:tags_count[i]});
}
And then sort on the count :
array.sort(function(a, b) {return a.count-b.count});
If you need to get your arrays back after that, you may do
for (var i=0; i<array.length; i++) {
tags[i] = array[i].tag;
tags_count[i] = array[i].count;
}
Demonstration
Assuming that both tags and tags_count are arrays with the same length (that part of the question wasn't too clear), the following is one way to do the trick.
var tags_array = new Array();
for (var i = 0; i < tags.length; i++)
{
tags_array[i] = {};
tags_array[i].tagName = tags[i];
tags_array[i].tagCount = tags_count[i];
}
tags_array.sort(function(a,b){return b.tagCount-a.tagCount});
One should note that it might be possible to structure the data in this way from the start instead of rewriting it like this, in which case that is preferable. Likewise, a better structure can be used to save the data, but this will work.
I have an array of strings in Javascript like `var elements = ["string1", "string2"]; The array is created dynamically so it could contain any number of strings. I want to associate a counter to each element of the array. The counter will increment or decrement during the webpage's life.
I was going to try element["string1"].counter = 1; but it didn't work.
What's a good way to implement this?
If you had an array var elements = ["string1", "string2"], you could not access an element with elements["string1"], you are using the value not the index. elements[0] is the correct form of access to the element, using the numerical key.
Even then, strings are special types of object and do not appear to take additional parameters readily, at least not when I tested a moment ago. Which is odd.
You could quickly knock the array in to a set of objects with separate text and counter components.
var elements = ["string1", "string2"];
var elementsWithCounter = [];
for(var index = 0; index < elements.length; index++) {
elementsWithCounter[i] = { text: elements[index], counter: 1 };
}
You could also create a "hash table" using a plain object such as:
var counter = {};
for(var i = elements.length; i--; ) {
counter[elements[i]] = 1;
}
Then you could increment the counter with:
counter['string1'] += 1;
or
counter[elements[0]] += 1;
This might help you.
elementArray = ["string1", "string2"]
function setCounter(str, val) {
for (var i = 0; i < elementArray.length; i++) {
if (str === elementArray[i]) elementArray[i].counter = val;
}
}
function getCounter(str) {
for (var i = 0; i < elementArray.length; i++) {
if (str === elementArray[i]) return elementArray[i].counter;
}
}
setCounter("string1", 5);
getCounter("string1");
Alternatively just access elementArray[index].counter
Javascript primitives/built in objects can't have properties/attributes added to their prototype (i.e. String.prototype.counter = -1 doesn't work correctly). Image, String, Date, Array all can't have properties added.
Maybe instead of a string you should make it an object, similar to what Orbling has posted.