String.prototype.toUpperCase()

¥Syntax

toUpperCase()

¥Parameters

没有任何。

¥None.

¥Return value

表示调用字符串转换为大写的新字符串。

¥A new string representing the calling string converted to upper case.

¥Description

toUpperCase() 方法返回转换为大写的字符串值。此方法不会影响字符串本身的值，因为 JavaScript 字符串是不可变的。

¥The toUpperCase() method returns the value of the string converted to uppercase. This method does not affect the value of the string itself since JavaScript strings are immutable.

¥Examples

¥Basic usage

console.log("alphabet".toUpperCase()); // 'ALPHABET'

¥Conversion of non-string this values to strings

当你将 this 设置为非字符串值时，此方法会将任何非字符串值转换为字符串：

¥This method will convert any non-string value to a string, when you set its this to a value that is not a string:

const a = String.prototype.toUpperCase.call({
  toString() {
    return "abcdef";
  },
});

const b = String.prototype.toUpperCase.call(true);

// prints out 'ABCDEF TRUE'.
console.log(a, b);

¥See also

• String.prototype.toLocaleLowerCase()
• String.prototype.toLocaleUpperCase()
• String.prototype.toLowerCase()