String.prototype.at()
- Standard built-in objects
String- Properties
- Methods
String.prototype[@@iterator]()String.prototype.anchor()String.prototype.at()String.prototype.big()String.prototype.blink()String.prototype.bold()String.prototype.charAt()String.prototype.charCodeAt()String.prototype.codePointAt()String.prototype.concat()String.prototype.endsWith()String.prototype.fixed()String.prototype.fontcolor()String.prototype.fontsize()String.fromCharCode()String.fromCodePoint()String.prototype.includes()String.prototype.indexOf()String.prototype.italics()String.prototype.lastIndexOf()String.prototype.link()String.prototype.localeCompare()String.prototype.match()String.prototype.matchAll()String.prototype.normalize()String.prototype.padEnd()String.prototype.padStart()String.raw()String.prototype.repeat()String.prototype.replace()String.prototype.replaceAll()String.prototype.search()String.prototype.slice()String.prototype.small()String.prototype.split()String.prototype.startsWith()String.prototype.strike()String.prototype.sub()String.prototype.substr()String.prototype.substring()String.prototype.sup()String.prototype.toLocaleLowerCase()String.prototype.toLocaleUpperCase()String.prototype.toLowerCase()String.prototype.toSource()String.prototype.toString()String.prototype.toUpperCase()String.prototype.trim()String.prototype.trimEnd()String.prototype.trimStart()String.prototype.valueOf()
- Inheritance:
Function- Properties
- Methods
Object- Properties
- Methods
Object.prototype.__defineGetter__()Object.prototype.__defineSetter__()Object.prototype.__lookupGetter__()Object.prototype.__lookupSetter__()Object.prototype.hasOwnProperty()Object.prototype.isPrototypeOf()Object.prototype.propertyIsEnumerable()Object.setPrototypeOf()Object.prototype.toLocaleString()Object.prototype.toSource()Object.prototype.toString()Object.prototype.valueOf()
The at() method takes an integer value and returns a new String consisting of the single UTF-16 code unit located at the specified offset. This method allows for positive and negative integers. Negative integers count back from the last string character.
Syntax
at(index)
Parameters
index-
The index (position) of the string character to be returned. Supports relative indexing from the end of the string when passed a negative index; i.e. if a negative number is used, the character returned will be found by counting back from the end of the string.
Return value
A String consisting of the single UTF-16 code unit located at the specified position. Returns undefined if the given index can not be found.
Examples
Return the last character of a string
The following example provides a function which returns the last character found in a specified string.
// A function which returns the last character of a given string
function returnLast(arr) {
return arr.at(-1);
}
let invoiceRef = 'myinvoice01';
console.log( returnLast(invoiceRef) );
// Logs: '1'
invoiceRef = 'myinvoice02';
console.log( returnLast(invoiceRef) );
// Logs: '2'
Comparing methods
Here we compare different ways to select the penultimate (last but one) character of a String. Whilst all below methods are valid, it highlights the succinctness and readability of the at() method.
const myString = 'Every green bus drives fast.';
// Using length property and charAt() method
const lengthWay = myString.charAt(myString.length-2);
console.log(lengthWay); // Logs: 't'
// Using slice() method
const sliceWay = myString.slice(-2, -1);
console.log(sliceWay); // Logs: 't'
// Using at() method
const atWay = myString.at(-2);
console.log(atWay); // Logs: 't'
Specifications
| Specification |
|---|
| Relative Indexing Method # sec-string-prototype-additions |
Browser compatibility
BCD tables only load in the browser
See also
- A polyfill of
String.prototype.atis available incore-js - A polyfill for the at() method.
String.prototype.indexOf()String.prototype.lastIndexOf()String.prototype.charCodeAt()String.prototype.codePointAt()String.prototype.split()