Differences between PHP functions and JavaScript functions

PHP and JavaScript function differences: Type declaration: PHP supports optional type declaration, JavaScript does not require it. Parameter passing: PHP passes parameters by value, JavaScript passes objects by reference. Return value: PHP uses the return statement to return a value, and JavaScript implicitly returns the value of the last expression. Scope: PHP follows block scoping, JavaScript follows lexical scoping.

Differences between PHP functions and JavaScript functions

Understanding the similarities and differences between PHP and JavaScript functions is crucial for developers important. While they both perform tasks, there are significant differences in how they work.

Type declaration

• PHP functions support optional type declaration, which specifies the data types of function parameters and return values.
• JavaScript is a weakly typed language, and there is no need to declare types when calling functions.

Passing parameters

• PHP functions pass parameters by value, that is, a copy of the parameter is passed. Changes made to parameters within a function will not affect the original value.
• JavaScript functions pass objects by reference, and changes made to parameters within the function will affect the original value.

Return value

• PHP functions can use the return statement to return one value or multiple values.
• JavaScript functions can implicitly return a value via the value of their last expression.

Scope

• PHP functions follow block scope, and variables are only visible inside the function.
• JavaScript functions follow lexical scope, and variables can also be accessed outside their declared scope.

Practical Case

Consider the following PHP function, which calculates the sum of two numbers:

function sum(int $num1, int $num2): int {
    return $num1 + $num2;
}

Now, consider a similar JavaScript Function:

function sum(num1, num2) {
    return num1 + num2;
}

In PHP functions, the int type declaration forces the parameter to be an integer and ensures that the return value is also an integer. In JavaScript functions, the types of parameters and return values ​​are automatically inferred and can be of any type.

Execute the following code to test the function:

$result = sum(10, 20);
echo $result; // 输出：30

const result = sum(10, 20);
console.log(result); // 输出：30

As you can see, PHP's type declaration ensures that the result is an integer, while JavaScript automatically infers that the result is a number.

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