JavaScript determines whether it is a symbol

In Javascript, you can use regular expressions or character encoding to determine whether a character is a symbol. A symbol refers to any character that is not a letter or number. This article will introduce several common methods to determine whether a character is a symbol.

1. Using regular expressions

In Javascript, regular expressions can be used to quickly and easily determine whether a character is a symbol. The following is a regular expression used to determine whether a character is a symbol:

const isSymbol = /[^ws]/;

In the regular expression, w represents a letter or number, and s represents a space character. So ¹ means any character that is not an alphabetic or numeric or space character. Use the test() method to determine whether a character matches the regular expression.

Sample code:

const isSymbol = /[^ws]/;
console.log(isSymbol.test("?")); // true，?是符号
console.log(isSymbol.test("a")); // false，a是字母
console.log(isSymbol.test("1")); // false，1是数字
console.log(isSymbol.test(" ")); // false，空格不是符号

2. Using character encoding

In the computer, each character has a corresponding character encoding. In ASCII encoding, the encoding range of symbols is 32-47, 58-64, 91-96, 123-126. We can use character encoding to determine whether a character is a symbol.

Sample code:

function isSymbol(char) {
  const code = char.charCodeAt(0);
  if ((code >= 32 && code <= 47) || (code >= 58 && code <= 64) ||
      (code >= 91 && code <= 96) || (code >= 123 && code <= 126)) {
    return true;
  }
  return false;
}

console.log(isSymbol("?")); // true，?是符号
console.log(isSymbol("a")); // false，a是字母
console.log(isSymbol("1")); // false，1是数字
console.log(isSymbol(" ")); // false，空格不是符号

3. Using Unicode encoding

Unicode is a character encoding standard that includes characters and symbols in almost all languages. We can use Unicode encoding to determine whether a character is a symbol.

Sample code:

function isSymbol(char) {
  const unicode = char.charCodeAt(0);
  if ((unicode >= 33 && unicode <= 47) || (unicode >= 58 && unicode <= 64) ||
      (unicode >= 91 && unicode <= 96) || (unicode >= 123 && unicode <= 126)) {
    return true;
  }
  return false;
}

console.log(isSymbol("?")); // true，?是符号
console.log(isSymbol("a")); // false，a是字母
console.log(isSymbol("1")); // false，1是数字
console.log(isSymbol(" ")); // false，空格不是符号

Summary

This article introduces three common methods of determining whether a character is a symbol, namely using regular expressions, character encoding and Unicode encoding. Using regular expressions is the easiest method, but there may be a performance loss; using character encoding and Unicode encoding is more cumbersome, but has higher performance. Readers can choose a method that suits them based on specific scenarios to determine whether a character is a symbol.

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