函数的JavaScript参数中的花括号 [英] Curly braces inside JavaScript parameters for functions

问题描述

函数的JavaScript参数周围的花括号有什么作用?

What do the curly braces surrounding JavaScript parameters for functions do?

var port = chrome.extension.connect({name: "testing"});
port.postMessage({found: (count != undefined)});

推荐答案

大括号表示对象文字.这是一种发送键/值对数据的方法.

The curly braces denote an object literal. It is a way of sending key/value pairs of data.

所以这个:

var obj = {name: "testing"};

用于访问数据.

obj.name; // gives you "testing"

只要键是唯一的，就可以给对象几个逗号分隔的键/值对.

You can give the object several comma separated key/value pairs, as long as the keys are unique.

var obj = {name: "testing",
           another: "some other value",
           "a-key": "needed quotes because of the hyphen"
          };

您还可以使用方括号访问对象的属性.

You can also use square brackets to access the properties of the object.

对于"a-key"，这是必需的.

obj["a-key"] // gives you "needed quotes because of the hyphen"

使用方括号，可以使用存储在变量中的属性名称访问值.

Using the square brackets, you can access a value using a property name stored in a variable.

var some_variable = "name";

obj[ some_variable ] // gives you "testing"

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