Merging objects in JavaScript can be a useful technique when working with complex data structures. There are several ways to merge objects, and the choice of method depends on the specific requirements of the task at hand.

One common approach to merging objects is to use the Object.assign() method. This method takes in one or more source objects and a target object, and it copies the properties from the source objects to the target object. If the target object already has a property with the same name, it will be overwritten by the value from the source object.

Here's an example of using Object.assign() to merge two objects:

```javascript

const target = { a: 1, b: 2 };

const source = { b: 3, c: 4 };

const result = Object.assign(target, source);

console.log(result); // { a: 1, b: 3, c: 4 }

```

In this example, the properties from the source object are merged into the target object, and the target object is modified in place. If you want to create a new object without modifying any of the source objects, you can pass an empty object as the target:

```javascript

const target = {};

const source1 = { a: 1 };

const source2 = { b: 2 };

const result = Object.assign(target, source1, source2);

console.log(result); // { a: 1, b: 2 }

```

Another way to merge objects is to use the spread operator (…) introduced in ES6. This operator can be used to spread the properties of an object into another object. Here's an example of using the spread operator to merge objects:

```javascript

const obj1 = { a: 1, b: 2 };

const obj2 = { b: 3, c: 4 };

const mergedObj = { ...obj1, ...obj2 };

console.log(mergedObj); // { a: 1, b: 3, c: 4 }

```

The spread operator creates a new object with the combined properties of the source objects. Unlike Object.assign(), the spread operator does not modify the source objects.

In summary, merging objects in JavaScript can be accomplished using methods like Object.assign() and the spread operator. Understanding these techniques can help you effectively combine data and simplify your code when working with complex data structures.