arrays
I have a very simple JavaScript array that may or may not contain duplicates.
var names = ["Mike","Matt","Nancy","Adam","Jenny","Nancy","Carl"];
I need to remove the duplicates and put the unique values in a new array.
I could point to all the code that I've tried but I think it's useless because they don't work. I accept jQuery solutions too.
How do I check if a variable is an array in JavaScript?
if (variable.constructor == Array)
In Java, you can use a for loop to traverse objects in an array as follows:
String[] myStringArray = {"Hello", "World"};
for (String s : myStringArray) {
// Do something
}
Can I do the same in JavaScript?
How do I check if an array includes a value in JavaScript?What is the most concise and efficient way to find out if a JavaScript array contains a value?
This is the only way I know to do it:
function contains(a, obj) {
for (var i = 0; i < a.length; i++) {
if (a[i] === obj) {
return true;
}
}
return false;
}
Is there a better and more concise way to accomplish this?
This is very closely related to Stack Overflow question Best way to find an item in a JavaScript Array? which addresses finding objects in an array using indexOf.
How do I append an object (such as a string or number) to an array in JavaScript?
Sort array of objects by string property valueI have an array of JavaScript objects:
var objs = [
{ first_nom: 'Lazslo', last_nom: 'Jamf' },
{ first_nom: 'Pig', last_nom: 'Bodine' },
{ first_nom: 'Pirate', last_nom: 'Prentice' }
];
How can I sort them by the value of last_nom in JavaScript?
I know about sort(a,b), but that only seems to work on strings and numbers. Do I need to add a toString() method to my objects?
I've got the following objects using AJAX and stored them in an array:
var homes = [
{
"h_id": "3",
"city": "Dallas",
"state": "TX",
"zip": "75201",
"price": "162500"
}, {
"h_id": "4",
"city": "Bevery Hills",
"state": "CA",
"zip": "90210",
"price": "319250"
}, {
"h_id": "5",
"city": "New York",
"state": "NY",
"zip": "00010",
"price": "962500"
}
];
How do I create a function to sort the objects by the price property in ascending or descending order using JavaScript only?
I have an array like this:
var arr1 = ["a", "b", "c", "d"];
How can I randomize / shuffle it?
How to create an array containing 1...NI'm looking for any alternatives to the below for creating a JavaScript array containing 1 through to N where N is only known at runtime.
var foo = [];
for (var i = 1; i <= N; i++) {
foo.push(i);
}
To me it feels like there should be a way of doing this without the loop.
How can I remove a specific item from an array in JavaScript?How do I remove a specific value from an array? Something like:
array.remove(value);
Constraints: I have to use core JavaScript. Frameworks are not allowed.
What's the simplest way to print a Java array?In Java, arrays don't override toString(), so if you try to print one directly, you get the className + '@' + the hex of the hashCode of the array, as defined by Object.toString():
int[] intArray = new int[] {1, 2, 3, 4, 5};
System.out.println(intArray); // Prints something like '[I@3343c8b3'
But usually, we'd actually want something more like [1, 2, 3, 4, 5]. What's the simplest way of doing that? Here are some example inputs and outputs:
// Array of primitives:
int[] intArray = new int[] {1, 2, 3, 4, 5};
// Output: [1, 2, 3, 4, 5]
// Array of object references:
String[] strArray = new String[] {"John", "Mary", "Bob"};
// Output: [John, Mary, Bob]
I've been told not to use for...in with arrays in JavaScript. Why not?
How do I declare and initialize an array in Java?
How do I determine whether an array contains a particular value in Java?I have a String[] with values like so:
public static final String[] VALUES = new String[] {"AB","BC","CD","AE"};
Given String s, is there a good way of testing whether VALUES contains s?
I am looking for a JavaScript array insert method, in the style of:
arr.insert(index, item)
Preferably in jQuery, but any JavaScript implementation will do at this point.
Loop (for each) over an array in JavaScriptHow can I loop through all the entries in an array using JavaScript?
Get the last item in an arrayHere is my JavaScript code so far:
var linkElement = document.getElementById("BackButton");
var loc_array = document.location.href.split('/');
var newT = document.createTextNode(unescape(capWords(loc_array[loc_array.length-2])));
linkElement.appendChild(newT);
Currently it takes the second to last item in the array from the URL. However, I want to do a check for the last item in the array to be "index.html" and if so, grab the third to last item instead.
Is there an easy way to delete an element from an array using PHP, such that foreach ($array) no longer includes that element?
I thought that setting it to null would do it, but apparently it does not work.
I want to write a script that loops through 15 strings (array possibly?) Is that possible?
Something like:
for databaseName in listOfNames
then
# Do something
end
Is there a way to empty an array and if so possibly with .remove()?
For instance,
A = [1,2,3,4];
How can I empty that?
Short circuit Array.forEach like calling break[1,2,3].forEach(function(el) {
if(el === 1) break;
});
How can I do this using the new forEach method in JavaScript? I've tried return;, return false; and break. break crashes and return does nothing but continue iteration.
I have an array of numbers that I need to make sure are unique. I found the code snippet below on the internet and it works great until the array has a zero in it. I found this other script here on Stack Overflow that looks almost exactly like it, but it doesn't fail.
So for the sake of helping me learn, can someone help me determine where the prototype script is going wrong?
Array.prototype.getUnique = function() {
var o = {}, a = [], i, e;
for (i = 0; e = this[i]; i++) {o[e] = 1};
for (e in o) {a.push (e)};
return a;
}
I have a need to add or prepend elements at the beginning of an array.
For example, if my array looks like below:
[23, 45, 12, 67]
And the response from my AJAX call is 34, I want the updated array to be like the following:
[34, 23, 45, 12, 67]
Currently I am planning to do it like this:
var newArray = [];
newArray.push(response);
for (var i = 0; i < theArray.length; i++) {
newArray.push(theArray[i]);
}
theArray = newArray;
delete newArray;
Is there a better way to do this? Does JavaScript have any built-in functionality that does this?
The complexity of my method is O(n) and it would be really interesting to see better implementations.
I'm trying to write a function that either accepts a list of strings, or a single string. If it's a string, then I want to convert it to an array with just the one item so I can loop over it without fear of an error.
So how do I check if the variable is an array?
With arrays, why is it the case that a[5] == 5[a]?As Joel points out in Stack Overflow podcast #34, in C Programming Language (aka: K & R), there is mention of this property of arrays in C: a[5] == 5[a]
Joel says that it's because of pointer arithmetic but I still don't understand. Why does a[5] == 5[a]?
Given an array of type Element[]:
Element[] array = {new Element(1), new Element(2), new Element(3)};
How do I convert this array into an object of type ArrayList<Element>?
ArrayList<Element> arrayList = ???;
How do I check if a particular key exists in a JavaScript object or array?
If a key doesn't exist, and I try to access it, will it return false? Or throw an error?
How to merge two arrays in JavaScript and de-duplicate itemsI have two JavaScript arrays:
var array1 = ["Vijendra","Singh"];
var array2 = ["Singh", "Shakya"];
I want the output to be:
var array3 = ["Vijendra","Singh","Shakya"];
The output array should have repeated words removed.
How do I merge two arrays in JavaScript so that I get only the unique items from each array in the same order they were inserted into the original arrays?
Copy array by valueWhen copying an array in JavaScript to another array:
var arr1 = ['a','b','c'];
var arr2 = arr1;
arr2.push('d'); //Now, arr1 = ['a','b','c','d']
I realized that arr2 refers to the same array as arr1, rather than a new, independent array. How can I copy the array to get two independent arrays?
I've got an array:
myArray = [{'id':'73','foo':'bar'},{'id':'45','foo':'bar'}, etc.]
I'm unable to change the structure of the array. I'm being passed an id of 45, and I want to get 'bar' for that object in the array.
How do I do this in JavaScript or using jQuery?
arrays