How to use the codePointAt method in JavaScript | Web Design and Web Developmen...
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by Janeth Kent
Date: 23-07-2021 javascript
The JavaScript codePointAt
method has more or less the same function as the charCodeAt
method, used to get the 16-bit Unicode representation of the character at a certain position in a string.
However, certain characters present a small problem, as they use two 16-bit units, so the charCodeAt
method will only return half of the representation of these special characters.
The codePointAt
method was introduced in JavaScript in its ES2015 version in order to get Unicode representations of characters that use two 16-bit units instead of just one. In general, you can get all Latin or Saxon characters using the charCodeAt
method, but not Chinese or Japanese characters. The codePointAt
method accepts as a parameter the index of the string to which the method is applied, which may be a standard string declared with single or double quotes, a String object or a template literal
The value returned by the codePointAt
method will be undefined when the index we pass to the method has no representation.
For example, to get the Unicode representation in decimal or hexadecimal formed by two Unicode UTF-16 units of the character we would have to use the charCodeAt
method twice:
// Decimal representation const firstPart = ''.charCodeAt(0); // 55362 const secondPart= ''.charCodeAt(1); // 57271 // Hexadecimal representation const firstPart = ''.charCodeAt(0).toString(16); // d842 const secondPart = ''.charCodeAt(1).toString(16); // dfb7
You can see that if you put both parts together and show them through the console, you get the character :
console.log('ud842udfb7'); //
However, it is possible to obtain the character representation using the
method only once:codePointAt
// Decimal representation const decimal = ''.codePointAt>(0); // 134071 // Hexadecimal representation const hexadecimal = ''.codePointAt(0).toString(16); // 20bb7
To check that the result is correct, simply display the result via the console:
console.log('u{20bb7}');
If you use a String
object, the process is exactly the same:
const mychain = new String(''); // Decimal representation const decimal = mychain.codePointAt(0); // 134071 // Hexadecimal representation const hexadecimal = mychain.codePointAt(0).toString(16); // 20bb7
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