CoffeeScript String substr()用法及代码示例

描述

此方法用于返回字符串的必需子字符串。它接受一个整数值，指示子字符串的起始值和字符串的长度，并返回所需的子字符串。如果起始值为负，则substr()方法将其用作字符串末尾的字符索引。

用法

下面给出的是substr()JavaScript 的方法。我们可以在 CoffeeScript 代码中使用相同的方法。

string.substr(start[, length])

示例

下面的例子演示了使用substr()CoffeeScript 代码中的 JavaScript 方法。将此代码保存在具有名称的文件中string_substr.coffee

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command prompt并编译 .coffee 文件，如下所示。

c:\> coffee -c coffee string_substr.coffee

在编译时，它会为您提供以下 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，打开command prompt再次运行 CoffeeScript 文件，如下所示。

c:\> coffee string_substr.coffee 

在执行时，CoffeeScript 文件产生以下输出。

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