charCodeAt()

描述 (Description)

此方法返回一个数字，指示给定索引处字符的Unicode值。

Unicode代码点的范围为0到1,114,111。 前128个Unicode代码点是ASCII字符编码的直接匹配。 charCodeAt()始终返回小于65,536的值。

语法 (Syntax)

下面给出了JavaScript的charCodeAt（）方法的语法。 我们可以使用CoffeeScript代码中的相同方法。

string. charCodeAt(index)

它接受表示String索引的整数值，并返回String的指定索引处存在的字符的Unicode值。 如果给定索引的值不在字符串长度的0到1之间，则返回NaN 。

例子 (Example)

以下示例演示了CoffeeScript代码中JavaScript的charCodeAt()方法的用法。 将此代码保存在名为string_charcodeat.coffee的文件中

str = "This is string"
console.log "The Unicode of the character at the index (0) is:" + str.charCodeAt 0 
console.log "The Unicode of the character at the index (1) is:" + str.charCodeAt 1 
console.log "The Unicode of the character at the index (2) is:" + str.charCodeAt 2 
console.log "The Unicode of the character at the index (3) is:" + str.charCodeAt 3 
console.log "The Unicode of the character at the index (4) is:" + str.charCodeAt 4 
console.log "The Unicode of the character at the index (5) is:" + str.charCodeAt 5

打开command prompt并编译.coffee文件，如下所示。

c:\> coffee -c string_charcodeat.coffee

在编译时，它为您提供以下JavaScript。

// Generated by CoffeeScript 1.10.0
(function() {
  var str;
  str = "This is string";
  console.log("The Unicode of the character at the index (0) is:" + str.charCodeAt(0));
  console.log("The Unicode of the character at the index (1) is:" + str.charCodeAt(1));
  console.log("The Unicode of the character at the index (2) is:" + str.charCodeAt(2));
  console.log("The Unicode of the character at the index (3) is:" + str.charCodeAt(3));
  console.log("The Unicode of the character at the index (4) is:" + str.charCodeAt(4));
  console.log("The Unicode of the character at the index (5) is:" + str.charCodeAt(5));
}).call(this);

现在，再次打开command prompt并运行CoffeeScript文件，如下所示。

c:\> coffee string_charcodeat.coffee

执行时，CoffeeScript文件生成以下输出。

The Unicode of the character at the index (0) is:84
The Unicode of the character at the index (1) is:104
The Unicode of the character at the index (2) is:105
The Unicode of the character at the index (3) is:115
The Unicode of the character at the index (4) is:32
The Unicode of the character at the index (5) is:105