CODEWITHSUNDEEP
javascriptjquery
Yuko Kasahara
Yuko Kasahara

Reputation: 113

What is this "[]" here doing?

Below is an extract from my textbook.

I have a question about the use of [] here in window.history[type](). I can tell that it's separating the object name(window) and the variable(type) so that they can be recognized as separate things but is there a name for this use of []? I performed a google search but nothing came up.

$(function() {
//omitted
['back', 'forward'].forEach(function(type) {
  $('.' + type).click(function() {
    window.history[type]();
    });
  });
});

Upvotes: 2

Views: 132

Answers (1)

jo_va
jo_va

Reputation: 13963

This is property/method access using bracket notation. In Javascript, you can access the properties of an object using the dot notation:

myObj.prop

Or the bracket notation:

myObj['prop']

When you dynamically construct the properties, however, you have no choice but to use bracket notation:

window.history['forward']()

is the same as 

window.history.forward()

Here you are iterating on the forward and back properties, and the bracket notation is used to call the functions from their string names on window.history.

Here is the doc linked by @Teemu

Upvotes: 5

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