Coffeescript 简明教程

CoffeeScript - Splat

在前面的章节中，我们已经看到了如何定义一个函数，调用一个函数和向函数传递参数。一般情况下，我们可以向函数传递固定数量的参数。在编程时，我们可能会遇到需要向这些函数传递可变参数的情况。在 JavaScript 中，我们使用对象来接受函数的可变数量的参数。

In the previous chapters, we have seen how to define a function and invoke a function and pass arguments to it. In general, we can pass a fixed number of arguments to a function. While programming, we may face situations where we need to pass variable arguments to these functions. In JavaScript, we use objects to accept variable number of arguments to a function.

CoffeeScript 提供了一个名为 splats 的特性来向函数传递多个参数。我们通过在参数名后放置三个点来在函数中使用星号，表示为 …​

CoffeeScript provides a feature called splats to pass multiple arguments to functions. We use splats in functions by placing three dots after the argument name and, it is denoted by …​

Syntax

下面给出了使用星号在函数中接受多个参数的语法。

Given below is the syntax of accepting multiple arguments within a function using splats.

my_function = (arguments...)->
   ............
   ............
   ............

Example

以下是使用 splats 接受函数中的多个参数的示例。这里我们使用了 splats 定义了一个名为 indian_team() 的函数。我们调用此函数三次，并且每次调用时分别传递 4 个玩家、6 个玩家和全部阵容。由于我们在函数定义中使用了 splats，因此每次调用它时它都会接受可变数量的参数。将此代码保存为一个名为 splats_definition.coffee 的文件。

Following is an example of accepting multiple arguments within a function, using splats. Here we have defined a function named indian_team() using splats. We are calling this function thrice and we are passing 4 players, 6 players, and full squad simultaneously, each time we call it. Since we have used splats in the function definition, it accepts variable number of arguments each time we call it. Save this code in a file with name splats_definition.coffee

indian_team = (first, second, others...) ->
  Captain = first
  WiseCaptain = second
  team  = others
  console.log "Captain: " +Captain
  console.log "Wise captain: " +WiseCaptain
  console.log "Other team members: " +team

#Passing 4 arguments
console.log "############## Four Players ############"
indian_team "Mahendra Singh Dhoni", "Virat Kohli", "Shikhar Dhawan", "Rohit Sharma"

#Passing 6 arguments
console.log "############## Six Players ############"
indian_team "Mahendra Singh Dhoni", "Virat Kohli", "Shikhar Dhawan", "Rohit Sharma", "Gurkeerat Singh Mann", "Rishi Dhawan"

#Passing full squad
console.log "############## Full squad #############"
indian_team "Mahendra Singh Dhoni", "Virat Kohli", "Shikhar Dhawan", "Rohit Sharma", "Gurkeerat Singh Mann", "Rishi Dhawan", "Ravindra Jadeja", "Axar Patel", "Jasprit Bumrah", "Umesh Yadav", "Harbhajan Singh", "Ashish Nehra", "Hardik Pandya", "Suresh Raina", "Yuvraj Singh", "Ajinkya Rahane"

打开 command prompt 并按照以下所示编译 .coffee 文件。

Open the command prompt and compile the .coffee file as shown below.

c:\> coffee -c splats_definition.coffee

编译后，它会给你以下 JavaScript。

On compiling, it gives you the following JavaScript.

// Generated by CoffeeScript 1.10.0
(function() {
  var indian_team,
    slice = [].slice;

  indian_team = function() {
    var Captain, WiseCaptain, first, others, second, team;
    first = arguments[0], second = arguments[1], others = 3 <= arguments.length ? slice.call(arguments, 2) : [];
    Captain = first;
    WiseCaptain = second;
    team = others;
    console.log("Captain: " + Captain);
    console.log("Wise captain: " + WiseCaptain);
    return console.log("Other team members: " + team);
  };

  console.log("############## Four Players ############");

  indian_team("Mahendra Singh Dhoni", "Virat Kohli", "Shikhar Dhawan", "Rohit Sharma");

  console.log("############## Six Players ############");

  indian_team("Mahendra Singh Dhoni", "Virat Kohli", "Shikhar Dhawan", "Rohit Sharma", "Gurkeerat Singh Mann", "Rishi Dhawan");

  console.log("############## Full squad #############");

  indian_team("Mahendra Singh Dhoni", "Virat Kohli", "Shikhar Dhawan", "Rohit Sharma", "Gurkeerat Singh Mann", "Rishi Dhawan", "Ravindra Jadeja", "Axar Patel", "Jasprit Bumrah", "Umesh Yadav", "Harbhajan Singh", "Ashish Nehra", "Hardik Pandya", "Suresh Raina", "Yuvraj Singh", "Ajinkya Rahane");

}).call(this);

现在，再次打开 command prompt 并按照以下所示运行 CoffeeScript 文件。

Now, open the command prompt again and run the CoffeeScript file as shown below.

c:\> coffee splats_definition.coffee

执行后，CoffeeScript 文件产生以下输出。

On executing, the CoffeeScript file produces the following output.

############## Four Players ############
Captain: Mahendra Singh Dhoni
Wise captain: Virat Kohli
Other team members: Shikhar Dhawan,Rohit Sharma
############## Six Players ############
Captain: Mahendra Singh Dhoni
Wise captain: Virat Kohli
Other team members: Shikhar Dhawan,Rohit Sharma,Gurkeerat Singh Mann,Rishi Dhawan
############## Full squad #############
Captain: Mahendra Singh Dhoni
Wise captain: Virat Kohli
Other team members: Shikhar Dhawan,Rohit Sharma,Gurkeerat Singh Mann,Rishi Dhawan,Ravindra Jadeja,Axar Patel,Jasprit Bumrah,Umesh Yadav,Harbhajan Singh,Ashish Nehra,Hardik Pandya,Suresh Raina,Yuvraj Singh,Ajinkya Rahane

Calling Functions using Splats

我们还可以使用 splats 调用函数。为此，我们必须创建一个包含要传递给函数的元素的数组，并且我们必须调用函数，方法是传递点缀有三个点的数组，如下所示。

We can also call a function using splats. For that, we have to create an array holding the elements we need to pass to the function, and we have to call the function by passing the array suffixed by three dots as shown below.

my_function values...

Example

以下是使用 splats 调用函数的示例。将此代码保存为一个名为 splats_call.coffee 的文件。

Following is an example of calling a function using splats. Save this code in a file with name splats_call.coffee

indian_team = (first, second, others...) ->
  Captain = first
  WiseCaptain = second
  team  = others
  console.log "Captain: " +Captain
  console.log "Wise captain: " +WiseCaptain
  console.log "Other team members: " +team

squad = [
   "Mahendra Singh Dhoni"
   "Virat Kohli"
   "Shikhar Dhawan"
   "Rohit Sharma"
   "Gurkeerat Singh Mann"
   "Rishi Dhawan"
   "R Ashwin"
   "Ravindra Jadeja"
   "Axar Patel"
   "Jasprit Bumrah"
   "Umesh Yadav"
   "Harbhajan Singh"
   "Ashish Nehra"
   "Hardik Pandya"
   "Suresh Raina"
   "Yuvraj Singh"
   "Ajinkya Rahane"
 ]

indian_team squad...

打开 command prompt 并按照以下所示编译 .coffee 文件。

Open the command prompt and compile the .coffee file as shown below.

c:\> coffee -c splats_call.coffee

编译后，它会给你以下 JavaScript。

On compiling, it gives you the following JavaScript.

// Generated by CoffeeScript 1.10.0
(function() {
  var indian_team, squad,
    slice = [].slice;

  indian_team = function() {
    var Captain, WiseCaptain, first, others, second, team;
    first = arguments[0], second = arguments[1], others = 3 <= arguments.length ? slice.call(arguments, 2) : [];
    Captain = first;
    WiseCaptain = second;
    team = others;
    console.log("Captain: " + Captain);
    console.log("Wise captain: " + WiseCaptain);
    return console.log("Other team members: " + team);
  };

  squad = ["Mahendra Singh Dhoni", "Virat Kohli", "Shikhar Dhawan", "Rohit Sharma", "Gurkeerat Singh Mann", "Rishi Dhawan", "R Ashwin", "Ravindra Jadeja", "Axar Patel", "Jasprit Bumrah", "Umesh Yadav", "Harbhajan Singh", "Ashish Nehra", "Hardik Pandya", "Suresh Raina", "Yuvraj Singh", "Ajinkya Rahane"];

  indian_team.apply(null, squad);

}).call(this);

现在，再次打开 command prompt 并按照以下所示运行 CoffeeScript 文件。

Now, open the command prompt again and run the CoffeeScript file as shown below.

c:\> coffee splats_call.coffee

执行后，CoffeeScript 文件产生以下输出。

On executing, the CoffeeScript file produces the following output.

Captain: Mahendra Singh Dhoni
Wise captain: Virat Kohli
Other team members: Shikhar Dhawan,Rohit Sharma,Gurkeerat Singh Mann,Rishi Dhawan,R Ashwin,Ravindra Jadeja,Axar Patel,Jasprit Bumrah,Umesh Yadav,Harbhajan Singh,Ashish Nehra,Hardik Pandya,Suresh Raina,Yuvraj Singh,Ajinkya Rahane

Splats with a Tailing Argument

我们还可以将尾部参数传递给 splats。在下面给出的示例中，我们在 splat 的后面传递了一个名为 last 的尾部参数。将此示例保存为一个名为 tailing_arguments.coffee 的文件。

We can also pass tailing arguments to splats. In the example given below, we have passed a tailing argument named last after the splat. Save this example in a file with the name tailing_arguments.coffee

indian_team = (first, second, others..., last) ->
  Captain = first
  WiseCaptain = second
  team  = others
  Wicketkeeper =last
  console.log "Captain: " +Captain
  console.log "Wise captain: " +WiseCaptain
  console.log "Wicket keeper is:"+last
  console.log "Other team members: " +team

squad = [
   "Mahendra Singh Dhoni"
   "Virat Kohli"
   "Shikhar Dhawan"
   "Rohit Sharma"
   "Gurkeerat Singh Mann"
   "Rishi Dhawan"
   "R Ashwin"
   "Ravindra Jadeja"
   "Axar Patel"
   "Jasprit Bumrah"
   "Umesh Yadav"
   "Harbhajan Singh"
   "Ashish Nehra"
   "Hardik Pandya"
   "Suresh Raina"
   "Yuvraj Singh"
   "Ajinkya Rahane"
 ]

indian_team squad...

打开 command prompt 并按照以下所示编译 .coffee 文件。

Open the command prompt and compile the .coffee file as shown below.

c:\> coffee -c tailing_arguments.coffee

编译后，它会给你以下 JavaScript。

On compiling, it gives you the following JavaScript.

// Generated by CoffeeScript 1.10.0
(function() {
  var indian_team, squad,
    slice = [].slice;

  indian_team = function() {
    var Captain, Wicketkeeper, WiseCaptain, first, i, last, others, second, team;
    first = arguments[0], second = arguments[1], others = 4 <= arguments.length ? slice.call(arguments, 2, i = arguments.length - 1) : (i = 2, []), last = arguments[i++];
    Captain = first;
    WiseCaptain = second;
    team = others;
    Wicketkeeper = last;
    console.log("Captain: " + Captain);
    console.log("Wise captain: " + WiseCaptain);
    console.log("Wicket keeper is:" + last);
    return console.log("Other team members: " + team);
  };

  squad = ["Mahendra Singh Dhoni", "Virat Kohli", "Shikhar Dhawan", "Rohit Sharma", "Gurkeerat Singh Mann", "Rishi Dhawan", "R Ashwin", "Ravindra Jadeja", "Axar Patel", "Jasprit Bumrah", "Umesh Yadav", "Harbhajan Singh", "Ashish Nehra", "Hardik Pandya", "Suresh Raina", "Yuvraj Singh", "Ajinkya Rahane"];

  indian_team.apply(null, squad);

}).call(this);

现在，再次打开 command prompt 并按照以下所示运行 CoffeeScript 文件。

Now, open the command prompt again and run the CoffeeScript file as shown below.

c:\> coffee tailing_arguments.coffee

执行后，CoffeeScript 文件产生以下输出。

On executing, the CoffeeScript file produces the following output.

Captain: Mahendra Singh Dhoni
Wise captain: Virat Kohli
Wicket keeper is:Ajinkya Rahane
Other team members: Shikhar Dhawan,Rohit Sharma,Gurkeerat Singh Mann,Rishi Dhawan,R Ashwin,Ravindra Jadeja,Axar Patel,Jasprit Bumrah,Umesh Yadav,Harbhajan Singh,Ashish Nehra,Hardik Pandya,Suresh Raina,Yuvraj Singh

Comprehensions with Splats

在函数内，我们还可以使用解析在 splat 的元素，如下面的示例所示。将此代码保存为一个名为 splats_comprehensions.coffee 的文件。

Within the function, we can also iterate the elements of a splat using comprehensions as shown in the following example. Save this code in a file with the name splats_comprehensions.coffee

indian_team = (first, second, others...) ->
  Captain = first
  WiseCaptain = second
  team  = others
  console.log "Captain: " +Captain
  console.log "Wise captain: " +WiseCaptain
  console.log "Other team members:: "
  console.log member for member in others

squad = [
   "Mahendra Singh Dhoni"
   "Virat Kohli"
   "Shikhar Dhawan"
   "Rohit Sharma"
   "Gurkeerat Singh Mann"
   "Rishi Dhawan"
   "R Ashwin"
   "Ravindra Jadeja"
   "Axar Patel"
   "Jasprit Bumrah"
   "Umesh Yadav"
   "Harbhajan Singh"
   "Ashish Nehra"
   "Hardik Pandya"
   "Suresh Raina"
   "Yuvraj Singh"
   "Ajinkya Rahane"
 ]

indian_team squad...

打开 command prompt 并按照以下所示编译 .coffee 文件。

Open the command prompt and compile the .coffee file as shown below.

c:\> coffee -c splats_comprehensions.coffee

编译后，它会给你以下 JavaScript。

On compiling, it gives you the following JavaScript.

// Generated by CoffeeScript 1.10.0
(function() {
  var indian_team, squad,
    slice = [].slice;

  indian_team = function() {
    var Captain, WiseCaptain, first, i, len, member, others, results, second, team;
    first = arguments[0], second = arguments[1], others = 3 <= arguments.length ? slice.call(arguments, 2) : [];
    Captain = first;
    WiseCaptain = second;
    team = others;
    console.log("Captain: " + Captain);
    console.log("Wise captain: " + WiseCaptain);
    console.log("Other team members:: ");
    results = [];
    for (i = 0, len = others.length; i < len; i++) {
      member = others[i];
      results.push(console.log(member));
    }
    return results;
  };

  squad = ["Mahendra Singh Dhoni", "Virat Kohli", "Shikhar Dhawan", "Rohit Sharma", "Gurkeerat Singh Mann", "Rishi Dhawan", "R Ashwin", "Ravindra Jadeja", "Axar Patel", "Jasprit Bumrah", "Umesh Yadav", "Harbhajan Singh", "Ashish Nehra", "Hardik Pandya", "Suresh Raina", "Yuvraj Singh", "Ajinkya Rahane"];

  indian_team.apply(null, squad);

}).call(this);

现在，再次打开 command prompt 并按照以下所示运行 CoffeeScript 文件。

Now, open the command prompt again and run the CoffeeScript file as shown below.

c:\> coffee splats_comprehensions.coffee

执行后，CoffeeScript 文件产生以下输出。

On executing, the CoffeeScript file produces the following output.

Captain: Mahendra Singh Dhoni
Wise captain: Virat Kohli
Other team members::
Shikhar Dhawan
Rohit Sharma
Gurkeerat Singh Mann
Rishi Dhawan
R Ashwin
Ravindra Jadeja
Axar Patel
Jasprit Bumrah
Umesh Yadav
Harbhajan Singh
Ashish Nehra
Hardik Pandya
Suresh Raina
Yuvraj Singh
Ajinkya Rahane