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To separate an integer into separate digits in an array in JavaScript, we use the split method.

For instance, we write

const n = 123456789;
const digits = n.toString().split("");

to call toString to convert n to a string.

Then we call split to split the string into the individual digit strings.

To store a byte array in JavaScript, we use the Unint8Array constructor.

For instance, we write

const array = new Uint8Array(100);
array[10] = 256;
console.log(array[10] === 0);

to create an Uint8Array array with 100 bytes.

Then we set the content of byte 11 to 256.

And then we check that its value is the same as 0, which is true since it’s 8 bits.

To copy all items from one array into another with JavaScript, we use the spread operator.

For instance, we write

const objArray = [
  { name: "first" },
  { name: "second" },
  { name: "third" },
  { name: "fourth" },
];
const clonedArr = [...objArray];

to use the spread operator to spread the objArray entries into a new array by copying each entry.

To print object array in JavaScript, we call the JSON.stringify method.

For instance, we write

const lineChartData = [
  {
    date: new Date(2022, 10, 2),
    value: 5,
  },
  {
    date: new Date(2022, 10, 25),
    value: 30,
  },
  {
    date: new Date(2022, 10, 26),
    value: 72,
    customBullet: "images/redstar.png",
  },
];

document.getElementById("whereToPrint").innerHTML = JSON.stringify(
  lineChartData,
  null,
  2
);

to call JSON.stringify to convert the lineChartData array into a JSON string with each level indented with 2 spaces.

Then we set that as the value of the element’s innerHTML property to render the JSON string in the element as its content.

To iterate array keys in JavaScript, we use the Object.keys method to get an array of string keys from the array.

For instance, we write

const array = [];
widthRange[46] = { sel: 46, min: 0, max: 52 };
widthRange[66] = { sel: 66, min: 52, max: 70 };
widthRange[90] = { sel: 90, min: 70, max: 94 };
const keys = Object.keys(array);

to call Object.keys with array to return an array of indexes of the array array.