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String.prototype.at()

20223

at() String UTF-16

const sentence = "The quick brown fox jumps over the lazy dog.";

let index = 5;

console.log(`An index of ${index} returns the character ${sentence.at(index)}`);
// Expected output: "An index of 5 returns the character u"

index = -4;

console.log(`An index of ${index} returns the character ${sentence.at(index)}`);
// Expected output: "An index of -4 returns the character d"

js
at(index)

index

UTF-16 String undefined

js
// 
function returnLast(arr) {
  return arr.at(-1);
}

let invoiceRef = "myinvoice01";

console.log(returnLast(invoiceRef));
// Logs: '1'

invoiceRef = "myinvoice02";

console.log(returnLast(invoiceRef));
// Logs: '2'

String at()

js
const myString = "Every green bus drives fast.";

//  length  charAt() 
const lengthWay = myString.charAt(myString.length - 2);
console.log(lengthWay); // 't'

//  slice() 
const sliceWay = myString.slice(-2, -1);
console.log(sliceWay); // 't'

//  at() 
const atWay = myString.at(-2);
console.log(atWay); // 't'

ECMAScript 2027 LanguageSpecification
# sec-string.prototype.at


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