JS: String.prototype

What is String.prototype

String.prototype is the value of the property key "prototype" of the function String. [see String Object]

String.hasOwnProperty("prototype")

Type

Type of String.prototype is Object .

typeof String.prototype === "object"

String.prototype is a string object.

console.log(
  Reflect.apply(Object.prototype.toString, String.prototype, []) ===
    "[object String]",
);

console.log(String.prototype.length === 0);
console.log("a" + String.prototype + "b" === "ab");

Parent

Parent of String.prototype is Object.prototype.

Reflect.getPrototypeOf(String.prototype) === Object.prototype

Purpose

Purpose of String.prototype is to provide methods and properties useful for all string objects.

String.prototype is the parent of all string objects.

console.log(
  Reflect.getPrototypeOf(Object("abc")) === String.prototype,
);

// Object("abc") turns primitive to object type

Properties

• constructor
• length

join, trim, pad

• concat
• repeat
• trim
• trimStart
• trimEnd
• padStart
• padEnd

substring

• slice
• substring
• substr

Search string

• indexOf
• lastIndexOf
• includes
• startsWith
• endsWith

Search / replace with regex

• search
• match
• matchAll
• replace

Convert to array

• split

Convert letter case

• toLowerCase
• str.toUpperCase
• str.toLocaleLowerCase
• str.toLocaleUpperCase

Get character and Unicode

• charAt
• charCodeAt
• codePointAt

misc

str.toString

Return the string itself.

str.valueOf

Return the string itself.

str.localeCompare(str)

Return negative, 0, or positive integer, by comparing str with str, in a locale aware manner. https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/localeCompare

str.normalize(form)

normalize a string according to Unicode Standard Annex #15 Unicode Normalization Forms. https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/normalize

String.prototype[Symbol.iterator]

return the Iterator.