Максим

data: () => ({
  maxlen: 10,
  items: [
    'hello, world!!',
    'fuck the world',
    'fuck everything',
    '1234567890',
    'Lorem ipsum dolor sit amet, consectetur adipiscing elit,',
   ],
}),
methods: {
  short1: (str, maxlen) => str.length <= maxlen ? str : str.slice(0, maxlen) + '...',
  short2: (str, maxlen) => str.substring(0, maxlen) + (str.charAt(maxlen) && '...'),
  short3: (str, maxlen) => str.replace(RegExp(`(.{${maxlen}}).+`), '$1...'),
  short4: (str, maxlen) => str.replace(RegExp(`(?<=.{${maxlen}}).+`), '...'),
},

<input type="range" min="1" max="20" v-model="maxlen">
<span>{{ maxlen }}</span>

<div v-for="n in items">
  <div v-text="short1(n, maxlen)"></div>
  <div v-html="short2(n, maxlen)"></div>
  <div :text-content.prop="short3(n, maxlen)"></div>
  <div>{{ short4(n, maxlen) }}</div>
</div>

const text = 'night has rolled out redesigned 3d hd';
const blacklist = [ 'night', 'year', 'when', 'you', 'can' ];

const exist = blacklist.some(word => text.includes(word));

exist // true

// Тут, конечно, лучше какие-нибудь id сделать для однозначности
const circle = document.querySelector('.circle');
const arrow = document.querySelector('.arrow');

document.addEventListener('mousemove', (e) => {    
    const circleRect = circle.getBoundingClientRect();
    const circleCenterX = circleRect.left + circle.offsetWidth / 2;
    const circleCenterY = circleRect.top + circle.offsetHeight / 2;
    const deltaX = e.clientX - circleCenterX;
    const deltaY = e.clientY - circleCenterY;
    const angleInRadians = Math.atan2(deltaY, deltaX) - Math.PI / 2;
    const angleInDegrees = 180 * angleInRadians / Math.PI;
    const angleFrom0To360 = (angleInDegrees + 360) % 360;
    const shouldEffectBeApplied = deltaY < 0;
    
    if (shouldEffectBeApplied) {
        arrow.style.transform = `rotate(${angleFrom0To360}deg)`;
    }
});

.arrow {
    transition: transform .1s linear;
}

.flex {
   --gap: 20px;
   display: flex;
   flex-wrap: wrap;
   gap: var(--gap);
}

.item {
   width: calc(50% - var(--gap) / 2);
   height: 100px;
   background-color: red;
}

.flex {
  width: 600px;
  display: flex;
  flex-wrap: wrap;
  gap: 20px;
}

let arr = ['a', 'b', 'c', 'd', 'e'];
let obj = arr.reduce((a, v, i) => { a[i+1] = v; return a; }, {});

console.log(obj);

Мое решение:

let arr = ['a', 'b', 'c', 'd', 'e'];
let obj = {};
for (let i = 0; i <= arr.length; i++) {
obj[i + 1] += arr;
}
console.log(obj);

- obj[i + 1] += arr;
+ obj[i + 1] = arr;

- obj[i + 1] = arr;
+ obj[i + 1] = arr[i];

let arr = ['a', 'b', 'c', 'd', 'e'];
let obj = {};
for (let i = 1; i <= arr.length; i++) {
obj[i] = arr[i-1];
}
console.log(obj);

let arr = ['a', 'b', 'c', 'd', 'e'];
let obj = arr.reduce((a, c, i) =>  (a[i+1] = c, a), {});
console.log(obj);