JS: String.prototype

What is String.prototype

String.prototype is the value of the property key "prototype" of the function String. 〔see String Object〕

console.assert(Object.hasOwn(String, "prototype") === true);

Type

Type of String.prototype is Object .

console.assert(typeof String.prototype === "object");

String.prototype is a string object.

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

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

Parent

Parent of String.prototype is Object.prototype.

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

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

Properties

• JS: String.prototype.constructor
• JS: String.prototype.length

substring

• JS: String.prototype.slice
• JS: String.prototype.substring ❌
• JS: String.prototype.substr

Get character and Unicode

• JS: String.prototype.at (Extract Char at Index)
• JS: String.prototype.charAt (Extract Char at Index) ❌
• JS: String.prototype.charCodeAt (Char to Char ID) ❌
• JS: String.prototype.codePointAt (Char to Char ID) ❌

join, trim, pad

• JS: String.prototype.concat
• JS: String.prototype.repeat
• JS: String.prototype.trim
• JS: String.prototype.trimStart
• JS: String.prototype.trimEnd
• JS: String.prototype.padStart
• JS: String.prototype.padEnd

Search string

• JS: String.prototype.indexOf
• JS: String.prototype.lastIndexOf
• JS: String.prototype.includes
• JS: String.prototype.startsWith
• JS: String.prototype.endsWith

Search / replace with regex

• JS: String.prototype.search
• JS: String.prototype.match
• JS: String.prototype.matchAll
• JS: String.prototype.replace

Convert to array

• JS: String.prototype.split

Convert letter case

• JS: String.prototype.toLowerCase
• String.prototype.toUpperCase
• String.prototype.toLocaleLowerCase
• String.prototype.toLocaleUpperCase

misc

String.prototype.toString

Return the string itself.

String.prototype.valueOf

Return the string itself.

String.prototype.localeCompare(str)

Return negative, 0, or positive integer, by comparing this (binding) with str, in a locale aware manner.

String.prototype.normalize(form)

normalize a string according to Unicode Standard Annex #15 Unicode Normalization Forms.

String.prototype[Symbol.iterator]

return the Iterator.