Why Can\'t I Add Properties to a JavaScript String?

Limits on Property Additions to JavaScript Primitives

When confronted with a code that cannot add properties to a string primitive, it is essential to understand the fundamental nature of JavaScript primitives. In JavaScript, there are eight distinct types: seven primitive types and one non-primitive type:

• Primitive Types:

  • Undefined
  • Null
  • Boolean
  • Number
  • BigInt
  • String
  • Symbol

• Non-Primitive Type:

  • Object

Values associated with primitive types are known as primitive values and lack the ability to hold properties. Conversely, values of the Object non-primitive type are referred to as objects and can possess properties.

Property Assignment Behavior

When assigning a property to a variable, such as:

<code class="js">foo.bar = 'abc';</code>

the outcome depends on the type of foo's assigned value:

1. Undefined/Null: Results in an error.
2. Object: Defines or updates a property named 'bar' on the foo object and sets its value to 'abc'.

3. Any other type:

   • Strict Mode: TypeError: "Cannot assign to property 'bar' on foo: not an object."
   • Loose Mode: No operation, foo remains unchanged.

Therefore, assigning properties only makes sense for objects.

Case Specific: Cannot Extend String Primitive with Date Property

In the provided example, the variable test contains a value of type String. Thus, attempting to add a property fails.

<code class="js">test.test = "test inner";</code>

Workarounds for Sorting Dates on a Grid

If modifying the code to bind to date objects directly is impractical, consider these alternative solutions:

1. Use a library or framework capable of handling date sorting, such as moment.js.
2. Convert the date strings to a custom data type that can hold the original date value and use that custom type in the grid sorting process.
3. Override the grid's default sorting mechanism to handle date strings specifically, ensuring they are sorted chronologically.

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