`call()` vs. `apply()`: When to Use Which Function Invocation Method?

Function Invocation with call and apply

When invoking functions, programmers often encounter the options of using Function.prototype.apply() or Function.prototype.call(). This article explores the distinctions and use cases for both methods.

apply() vs. call()

The fundamental difference lies in how they handle function arguments:

• apply(): Accepts arguments as an array.
• call(): Requires arguments to be listed explicitly, separated by commas.

Syntax

Method	Syntax
apply()	function.apply(thisArg, [arg1, arg2, ...])
call()	function.call(thisArg, arg1, arg2, ...)

Mnemonics

To remember the difference:

• A for array: apply() takes an array of arguments.
• C for comma: call() requires arguments separated by commas.

Use Cases

• call(): Useful when passing a specific number of arguments.
• apply(): Ideal for scenarios where arguments are already stored in an array or require dynamic binding.

Performance Considerations

Both methods have similar performance characteristics. In ES6 and later, the spread operator (...) can be used with call(), providing a more concise alternative to apply().

Example

Consider the following function:

function greet(name, occupation) {
  console.log(`Hello, my name is ${name} and I'm a ${occupation}.`);
}

Invoking the function using apply() and call():

greet.apply(undefined, ["John", "engineer"]);
greet.call(undefined, "Mary", "doctor");

This will output:

Hello, my name is John and I'm a engineer.
Hello, my name is Mary and I'm a doctor.

The above is the detailed content of `call()` vs. `apply()`: When to Use Which Function Invocation Method?. For more information, please follow other related articles on the PHP Chinese website!