js array.at All In One

const arr = [1, 3, 5];
const index = 2;

console.log('arr[index] =', arr[index]);
// arr[index] = 5

console.log('arr.at(index) =', arr.at(index));
// arr.at(index) = 5

demo



const colors = ['red', 'green', 'blue'];

// 1. 使用 indexOf
const indexTarget = colors[colors.indexOf('green')];
console.log('indexTarget =', indexTarget);
// 'green'

// 2. 使用 length 计算
const lenTarget = colors[colors.length - 2];
console.log('lenTarget =', lenTarget);
// 'green'

// 3. 使用 slice
const sliceTarget = colors.slice(-2, -1);
console.log('sliceTarget =', sliceTarget[0]); 
// 'green'

// 4. 使用 at
const atTarget = colors.at(-2);
console.log('atTarget =', atTarget); 
// 'green'

// 5. 使用 index
const target = colors[-2]
console.log('target =', target); 
// 'green'