JS小函数-字符串的首字母大写

字符串的首字母大写，不能使用：

1. toUpperCase()
2. toLowerCase()

例子：

这次依旧没有我的答案。
1.

String.prototype.capitalize = function () {
let c = this.charCodeAt(0);
if (97 <= c && c <= 122) c -= 32;
return String.fromCharCode(c) + this.slice(1);
}

2.

String.prototype.capitalize = function(){
var map = {
a : 'A',
b : 'B',
c : 'C',
d : 'D',
e : 'E',
f : 'F',
g : 'G',
h : 'H',
i : 'I',
j : 'J',
k : 'K',
m : 'M',
n : 'N',
o : 'O',
p : 'P',
q : 'Q',
r : 'R',
s : 'S',
t : 'T',
u : 'U',
v : 'V',
w : 'W',
x : 'X',
y : 'Y',
z : 'Z'
};
return map[this[0]] ? map[this[0]] + this.slice(1) : this.toString();
};

3.

String.prototype.capitalize = function() {
return this.replace(/^[a-z]/, c => String.fromCharCode(c.charCodeAt(0)-32))
}

4.

String.prototype.capitalize = function() {
return /^[a-z]/.test(this) ? this.replace(this.charAt(0), String.fromCharCode(this.charCodeAt(0) - 32)) :
this.toString();
}

5.

String.prototype.capitalize = function()
{
var searchArray = 'abcdefghijklmnopqrstuvwxyz';
var replaceArray = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ';
var array = this.split('');
var index = searchArray.indexOf(array[0]);
if (index > -1) array[0] = replaceArray[index];
return array.join('');
}

6.

String.prototype.capitalize = function() {
var alf = 'abcdefghijklmnopqrstuvwxyz';
var alfC = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ';
var self = this.split('');
if (alf.indexOf(self[0]) != -1) {
self[0] = alfC[alf.indexOf(self[0])];
}
return self.join('');
}

7.

String.prototype.capitalize = function() {
if (this.charCodeAt(0) >= 97 && this.charCodeAt(0) <= 122) {
return (String.fromCharCode(this.charCodeAt(0) - 32) + this.slice(1));
}

return this.toString();
}

8.

String.prototype.capitalize = function() {
if (this.charCodeAt() < 97 || this.charCodeAt() > 122) return this.toString();
return String.fromCharCode(this.charCodeAt() - 32) + this.substring(1);
};