函数的 JavaScript 参数中的花括号

问题描述

围绕 JavaScript 函数参数的花括号有什么作用?

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

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

推荐答案

花括号表示一个对象字面量.这是一种发送数据键/值对的方式.

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"};

这样用来访问数据.

obj.name; // gives you "testing"

你可以给对象几个逗号分隔的键/值对，只要键是唯一的.

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来访问对象的属性.

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

这在 "a-key" 的情况下是必需的.

This would be required in the case of the "a-key".

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

使用方括号，您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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