fromCodePoint()方法的语法为：
String.fromCodePoint(num1, ..., numN) fromCodePoint()方法是静态方法，使用String类名称进行调用。
fromCodePoint()参数
fromCodePoint()方法采用：
- num1，…，numN-代码点序列。
从fromCodePoint()返回值
- 返回使用指定的代码点序列创建的字符串 。
注意事项 ：
- 如果给出了无效的Unicode代码点，
fromCodePoint()方法将引发RangeError。 -
fromCodePoint()方法返回一个字符串，而不是String对象。
示例：使用fromCodePoint()方法
let string1 = String.fromCodePoint(65, 66, 67);
console.log(string1); // ABC
let string2 = String.fromCharCode(72, 69, 76, 76, 79);
console.log(string2); // HELLO
// numbers can be passed as hexadecimals
let string3 = String.fromCodePoint(0x2f804);
console.log(string3); // "\uD87E\uDC04"
// unlike fromCharCode() that requires surrogate pair to return supplementary char
// fromCodePoint() can even return 4-byte supplementary chars
let string4 = String.fromCodePoint(0x1f303);
console.log(string4); // Unicode character "Night with Stars"
let string5 = String.fromCodePoint(Infinity);
console.log(string5); // RangeError输出
ABC
HELLO
\uD87E\uDC04
RangeError: Invalid code point Infinity 推荐阅读： JavaScript字符串fromCharCode()