CoffeeScript 字符串 - substr()

说明

此方法用于返回字符串所需的部分字符串。它接受一个整数值，表示部分字符串的起始值和字符串的长度，并返回所需的部分字符串。如果起始值是负数，则 substr() 方法将其用作字符串结尾的字符索引。

语法

下面给出了 JavaScript 的 substr() 方法的语法。我们可以在 CoffeeScript 代码中使用相同的方法。

string.substr(start[, length])

示例

以下示例演示了在 CoffeeScript 代码中使用 JavaScript 的 substr() 方法。将此代码保存在名为 string_substr.coffee 的文件中

str = "Apples are round, and apples are juicy.";
         
console.log "The sub string having start and length as (1,2) is : " + str.substr 1,2
console.log "The sub string having start and length as (-2,2) is : " + str.substr -2,2
console.log "The sub string having start and length as (1) is : " + str.substr 1
console.log "The sub string having start and length as (-20, 2) is : " + str.substr -20,2
console.log "The sub string having start and length as (20, 2) is : " + str.substr 20,2;

打开 命令提示符 并编译 .coffee 文件，如下所示。

c:\> coffee -c coffee string_substr.coffee

在编译时，它会给你以下 JavaScript。

// Generated by CoffeeScript 1.10.0
(function() {
  var str;

  str = "Apples are round, and apples are juicy.";

  console.log("The sub string having start and length as (1,2) is : " + str.substr(1, 2));

  console.log("The sub string having start and length as (-2,2) is : " + str.substr(-2, 2));

  console.log("The sub string having start and length as (1) is : " + str.substr(1));

  console.log("The sub string having start and length as (-20, 2) is : " + str.substr(-20, 2));

  console.log("The sub string having start and length as (20, 2) is : " + str.substr(20, 2));

}).call(this);

现在，再次打开 命令提示符 并运行 CoffeeScript 文件，如下所示。

c:\> coffee string_substr.coffee 

在执行时，CoffeeScript 文件会产生以下输出。

The sub string having start and length as (1,2) is : pp
The sub string having start and length as (-2,2) is : y.
The sub string having start and length as (1) is : pples are round, and apples are juicy.
The sub string having start and length as (-20, 2) is : nd
The sub string having start and length as (20, 2) is : d