JS: String.prototype

By Xah Lee. Date: . Last updated: .

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

substring

Get character and Unicode

join, trim, pad

Search string

Search / replace with regex

Convert to array

Convert letter case

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 JS: 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.

JavaScript. String