Question

以下声明是什么意思？

var line = {}, lines = [], hasmore;

我知道lines = []是一个数组，但我不了解其他数据。

实际代码是使用javascript xpcom

逐行读取文件

var line = {}, lines = [], hasmore;
do {
      hasmore = istream.readLine(line);
      lines.push(line.value); 
} while(hasmore);

Answer 1

它正在创建3个变量

var line = {};   // creates an object
var lines = [];  // creates an array
var hasmore;     // undefined

Answer 2

声明了3个变量（参见：Declaring Multiple Variables in JavaScript）。

var line = {}  // creates an empty object literal
    lines = [] // creates an empty array literal
    hasmore    // creates an empty undefined variable, which can hold any datatype

Answer 3

继续在您的控制台上尝试：

var line = {}, lines = [], hasmore;

然后访问它们你会看到：

line is Object, 
lines is an array 
hasmore is undefined

Javascript变量定义 - 澄清

3 个答案: