How to create an array in JavaScript whose indexing starts at 1?

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By default the indexing of every JavaScript array starts from 0. I want to create an array whose indexing starts from 1 instead.

I know, must be very trivial... Thanks for your help.

How to create an array in JavaScript whose indexing starts at 1 , function next_back(action) {\n"; //create JS array to hold all of our images in this and it would know that we are dealing with an array and starting on 1. before you can assign a value for image_list[index] you have to define image_list. JavaScript arrays are used to store multiple values in a single variable. An array is a special variable, which can hold more than one value at a time. If you have a list of items (a list of car names, for example), storing the cars in single variables could look like this: However, what if you want to loop through the cars and find a specific one?

Since this question also pops up for a Google search like "javascript start array at 1" I will give a different answer:

Arrays can be sliced. So you can get a sliced version of the Array like this:

var someArray = [0, 1, 2, 3];

someArray.slice(1);
[1, 2, 3]

someArray.slice(2, 4);
[2, 3]

Source: https://developer.mozilla.org/en/docs/Web/JavaScript/Reference/Global_Objects/Array/slice

Indexed collections, There are two syntaxes for creating an empty array: Array elements are numbered, starting with zero. get the object at index 1 and then show its name alert ( arr [ 1 ] . name ) ; // John // get the function at index 3 and run it  There are two ways to create an array in JavaScript: The array literal, which uses square brackets. The array constructor, which uses the new keyword. Let’s demonstrate how to create an array of shark species using the array literal, which is initialized with [].

A simple solution is to fill the zeroth item:

var map = [null, 'January', 'February', 'March'];
'First month : ' + map[1];

Semantically it would be better to use an object:

var map = {1:'January', 2:'February', 3:'March'};
'First month : ' + map[1];

Note these keys are not ints actually, object keys are always strings. Also, we can't use dot notation for accessing. (MDN - Property Accessors)

I'd choose the first solution, which I think is less confusing.

JS array starting at 1 instead of 0, Starting from the index 1 it removed 1 element. concat. The method arr.concat creates a new array that includes values from other arrays and  ) and keys method, enables you to create a temporary array of size N to produce the indexes, and then a new array that can be assigned to your variable: var foo = [ Array(N).keys() ]; Fill/Map. You can first create the size of the array you need, fill it with undefined and then create a new array using map, which sets each element to the index.

Okay, according to @cletus you couldn't do that because it's a built-in javascript feature but you could go slightly different way if you still want that. You could write your own index-dependent functions of Array (like reduce, map, forEach) to start with 1. It's not a difficult task but still ask yourself: why do I need that?

Array.prototype.mapWithIndexOne = function(func) {
  const initial = []
  for (let i = 1; i < this.length + 1; i++) {
    initial.push(func(this[i - 1], i))
  }
  return initial
}

const array = ['First', 'Second', 'Third', 'Fourth', 'Fifth']

console.log(array.mapWithIndexOne((element, index) => `${element}-${index}`))
// => ["First-1", "Second-2", "Third-3", "Fourth-4", "Fifth-5"]

Codepen: https://codepen.io/anon/pen/rvbNZR?editors=0012

Array, Keyword new. The following example also creates an Array, and assigns values to it: Note: Array indexes start with 0. [0] is the first element. [1] is the Try it Yourself ». The length property is always one more than the highest array index. At the implementation level, JavaScript's arrays actually store their elements as standard object properties, using the array index as the property name. The length property is special. It always returns the index of the last element plus one. (In the example below, 'Dusty' is indexed at 30, so cats.length returns 30 + 1).

You could use delete to remove the first element like so:

let arr = ['a','b','c'];
delete arr[0];

console.log(arr[0]);
console.log(arr[1]);

Arrays, Get the index of the first element in the array that has a value of 18 or more: array element (and does not check the remaining values); Otherwise it returns -1. In this case the program is supposed to add all the arrays together. However if I entered 1 in the sum method parameter it would start counting from 7 onwards but if I put 0 it outputs 0. public

Array methods, 28.6.1 Do you need to create an empty Array that you'll fill completely later on? To read an Array element, you put an index in square brackets (indices start multidimensional Arrays; you need to resort to Arrays whose elements are Arrays:​. We will begin by looking at different ways to create an array in JavaScript. The first two of these examples create arrays where only the length is set and there are no numbered entries at all. The second two create numbered entries from 0 to one less than the length.

JavaScript Arrays, Arrays. An array is a map from indices (natural numbers, starting at zero) to The preceding array has a hole: there is no element at index 1. can create an empty array with a given length or an array whose elements are the given values. Creating an array using the result of a match. The result of a match between a RegExp and a string can create a JavaScript array. This array has properties and elements which provide information about the match. Such an array is returned by RegExp.exec(), String.match(), and String.replace().

JavaScript Array findIndex() Method, Arrays in JavaScript are high-level list-like objects with a length property and integer properties as indexes. In this article, I share a couple of hacks for creating new JavaScript arrays or cloning already existing ones. Creating Arrays: The Array Constructor

Comments
  • Why do you want to do that? I ask because when you find yourself trying to circumvent one of the most basic characteristics of a programming language, odds are good there's a better way to do what you're trying to do.
  • And besides, starting array indices from 0 is a feature, not a bug.
  • If you want to display indices to a user you can just display i + 1. You really should just get used to zero indexes because you are going to run into so many fence-post errors in your lifetime if you work around it.
  • Impossible...dats surprising! Well, there's no useful reason for me to say...why I want to start at 1...just an idea. So, yeah..i guess, I have to adjust my indices accordingly, which is not a problem. Wanted to start at 1, just for the sake of it.
  • Now, 8 years later, you can use Map
  • How do I ignore index 0 in Javascript?
  • @josefdev - put a value there, and then never refer to it. I.E. a = ["ignore me", "this has index 1", "another string, at index 2"]; firstString = a[1]; However, this advice isn't very useful - built in functions such as for (s of a) won't 'know' that you want to ignore a[0] - the burden is entirely on you to find ways to code that don't use a[0]; it is more practical to get used to arrays starting at 0.
  • This just creates an array whose first value is 1. This question was about how to create an array where the first index is 1, which is a very different thing.
  • This doesn't work with many array methods. For example, Array.from(myArray.keys()) returns [0, 1, 2, 3, 4] instead of [1, 2, 3, 4, 5].
  • @Gothdo, i think you're wrong! ‌Because this result >> [0, 1, 2, 3, 4] has not any unexpected value for @detj (questioner). He just need ([0, 1, 2, 3, 4])[n] when n>=1.So this array always has correct result for him.