JavaScript - how to convert array of key-value tuples into object?

The Object.fromEntries() method does exactly what you need.

Note:

The Object.fromEntries() has been introduced in ECMAScript 2019 (ES10).

Practical example using fromEntries()  (ES10+)

// ONLINE-RUNNER:browser;

const array = [
    ['id', '1'],
    ['name', 'Tom'],
    ['age', '21'],
    ['premium', 'true'],
];

const object = Object.fromEntries(array);

console.log(JSON.stringify(object)); // { id: '1', name: 'Tom', age: '21', premium: 'true' }

Alternative solution using forEach()

This solution also works with older versions of JavaScript.

// ONLINE-RUNNER:browser;

var array = [
    ['id', '1'],
    ['name', 'Tom'],
    ['age', '21'],
    ['premium', 'true'],
];

var object = {};

array.forEach(function(data) {
    object[data[0]] = data[1];
});

console.log(JSON.stringify(object)); // { id: '1', name: 'Tom', age: '21', premium: 'true' }

See also

1. JavaScript - ECMAScript / ES versions and features

References

1. Object.fromEntries() - JavaScript | MDN
2. Array.prototype.forEach() - JavaScript | MDN