Primitive and Non-Primitive (Object) Data Types

Primitive and Non-Primitive (Object) Data Types:

• JavaScript:

  • Primitive Data Types: Number, String, Boolean, Null, Undefined, Symbol (added in ECMAScript 6).
  • Object Data Type: Objects (including arrays and functions) are non-primitive.

• PHP:

  • Primitive Data Types: Integer, Float, String, Boolean, Null.
  • Object Data Type: Objects (created from classes or built-in classes like stdClass).

Pass by Value vs. Pass by Reference:

• JavaScript:

  • Primitive Types: Passed by value. Changes inside a function do not affect the original value.
  • Objects (Non-Primitive): Passed by reference. Changes inside a function affect the original object.

• PHP:

  • Primitive Types: Passed by value.
  • Objects (Non-Primitive): Passed by reference. Changes inside a function affect the original object.

Comparison - JavaScript vs. PHP:

• JavaScript:

  • Syntax Example:

  let primitiveValue = 5;
  let objectValue = { key: 'value' };
  
  function modifyValues(a, b) {
    a = 10;
    b.key = 'modified';
  }
  
  modifyValues(primitiveValue, objectValue);
  console.log(primitiveValue);  // Output: 5
  console.log(objectValue.key); // Output: 'modified'
  

• PHP:

  • Syntax Example:

  $primitiveValue = 5;
  $objectValue = (object)['key' => 'value'];
  
  function modifyValues($a, $b) {
    $a = 10;
    $b->key = 'modified';
  }
  
  modifyValues($primitiveValue, $objectValue);
  echo $primitiveValue;        // Output: 5
  echo $objectValue->key;      // Output: 'modified'
  

In both languages, primitive types are passed by value, and objects (non-primitive) are passed by reference. The behavior ensures that changes made to objects inside a function are reflected outside the function.

Note: While objects in JavaScript are always passed by reference, primitive types are immutable, meaning their values cannot be changed. In PHP, it's possible to explicitly pass a variable by reference using the & symbol in the function parameter list.