The difference between initializing objects as null and empty objects in JS

In JavaScript, object types are complex data types, also known as reference data types.When we declare an object, we can assign some basic data to the object,

const person = {name: 'liudehua',age: 23}

But sometimes we declare an object and don't want to assign a value to the object, so there are two ways to initialize the object.

 // Method 1, directly give an empty objectconst person = {};// Method 2, assign the object to nullconst person1 = null

But there are some differences between the two methods:

1. When converting to a boolean value, an empty object will be converted to true, and null will be converted to false. When we directly use the object variable name to make some judgments, we need to pay attention:

    // Method 1, directly give an empty objectconst person = {};// Method 2, assign the object to nullconst person1 = nullif(person) {console.log("will execute");}if(person1) {console.log("will not execute");}

2. Understanding at the memory level, when it is declared as an empty object, it will still open up a memory space in the heap memory. When it is declared as null, the reference will point to a 0x0 memory location, not in the heap memory.Create a memory space.
3. But when we use the typeof operator to operate on empty objects and values ​​of type null, the return values ​​are all of type object

    // Method 1, directly give a nullobjectconst person = {};// Method 2, assign the object to nullconst person1 = nullconsole.log(typeof person); // objectconsole.log(typeof person1); // object

Summary: When declaring an object, if you don't need to assign a specific value, but only need to initialize it, it is recommended to assign it to null.