首先,为什么会有CoffeeScript这种东西,原因特别简单,为了弥补JavaScript的不足。它的运行原理特别简单,按照它的语法编写程序,在丢到浏览器运行之前需要使用它的编译器编译成JavaScript代码。理论上,也属于编译语言,只不过传统上我们认识的编译语言都是编译成二进制
使用之前需要安装
npm install coffeescript
如果你没有使用npm管理器,可以直接到Github主页下载源码Build一下就好
当你写好了CoffeeScript代码,只需要简单一句话即可编译
coffee -c /path/to/script.coffee
CoffeeScript的语法特别简洁,没有分号结束,对象的定义以及函数的调用都简单到爆
# Assignment:
number = 42
opposite = true
# Conditions:
number = -42 if opposite
# Functions:
square = (x) -> x * x
# Arrays:
list = [1, 2, 3, 4, 5]
# Objects:
math =
root: Math.sqrt
square: square
cube: (x) -> x * square x
# Splats:
race = (winner, runners...) ->
print winner, runners
# Existence:
alert "I knew it!" if elvis?
# Array comprehensions:
cubes = (math.cube num for num in list)
编译结果
// Assignment:
var cubes, list, math, num, number, opposite, race, square;
number = 42;
opposite = true;
if (opposite) {
// Conditions:
number = -42;
}
// Functions:
square = function(x) {
return x * x;
};
// Arrays:
list = [1, 2, 3, 4, 5];
// Objects:
math = {
root: Math.sqrt,
square: square,
cube: function(x) {
return x * square(x);
}
};
// Splats:
race = function(winner, ...runners) {
return print(winner, runners);
};
if (typeof elvis !== "undefined" && elvis !== null) {
// Existence:
alert("I knew it!");
}
// Array comprehensions:
cubes = (function() {
var i, len, results;
results = [];
for (i = 0, len = list.length; i < len; i++) {
num = list[i];
results.push(math.cube(num));
}
return results;
})();
目前唯一的问题是不好Debug,如果它的生态圈足够强大,未来这一个问题解决之后会更好