how to get key value pair in javascript array code example

Example 1: javascript iterate over object keys and values

const object1 = {
  a: 'somestring',
  b: 42
};

for (let [key, value] of Object.entries(object1)) {
  console.log(`${key}: ${value}`);
}

// expected output:
// "a: somestring"
// "b: 42"
// order is not guaranteed

Example 2: js key value array

var myArray = {id1: 100, id2: 200, "tag with spaces": 300};
myArray.id3 = 400;
myArray["id4"] = 500;

for (var key in myArray) {
  console.log("key " + key + " has value " + myArray[key]);
}

Example 3: array of array key value javascript

var categories = [
    {"1":"Category 1"},
    {"2":"Category 2"},
    {"3":"Category 3"},
    {"4":"Category 4"}
];