'string text' "string text" " espaol deutsch English   portugus       "

String

String(thing)

thing

ECMAScript 2015Template literals

`hello world` `hello! world!` `hello ${who}` escape `<a>${who}</a>`

+

let longString =
  "This is a very long string which needs " +
  "to wrap across multiple lines because " +
  "otherwise my code is unreadable.";

"\"

let longString =
  "This is a very long string which needs \
to wrap across multiple lines because \
otherwise my code is unreadable.";

length + += indexOf ? substring

charAt

return "cat".charAt(1); //  "a"

( ECMAScript 5 )

return "cat"[1]; //  "a"

( Object.defineProperty)

C strcmp() JavaScript

var a = "a";
var b = "b";
if (a < b)
  // true
  print(a + "  " + b);
else if (a > b) print(a + "  " + b);
else print(a + "  " + b + " ");

String localeCompare

string String

JavaScript String (Boolean Numbers )

String literals (denoted by double or single quotes) and strings returned from String calls in a non-constructor context (i.e., without using the new keyword) are primitive strings. JavaScript automatically converts primitives to String objects, so that it's possible to use String object methods for primitive strings. In contexts where a method is to be invoked on a primitive string or a property lookup occurs, JavaScript will automatically wrap the string primitive and call the method or perform the property lookup.

var s_prim = "foo";
var s_obj = new String(s_prim);

console.log(typeof s_prim); //  "string"
console.log(typeof s_obj); //  "object"

String eval eval String

s1 = "2 + 2"; // 
s2 = new String("2 + 2"); // 
console.log(eval(s1)); //  4
console.log(eval(s2)); //  "2 + 2"

String

String valueOf

console.log(eval(s2.valueOf())); //  4

String

String.fromCharCode()

Unicode

String.fromCodePoint()

String

The String instance methods are also available in Firefox as of JavaScript 1.6 (though not part of the ECMAScript standard) on the String object for applying String methods to any object:

var num = 15;
alert(String.replace(num, /5/, "2"));

Generics are also available on Array methods.

The following is a shim to provide support to non-supporting browsers:

/*globals define*/
// Assumes all supplied String instance methods already present
// (one may use shims for these if not available)
(function () {
  "use strict";

  var i,
    // We could also build the array of methods with the following, but the
    //   getOwnPropertyNames() method is non-shimable:
    // Object.getOwnPropertyNames(String).filter(function (methodName)
    //  {return typeof String[methodName] === 'function'});
    methods = [
      "quote",
      "substring",
      "toLowerCase",
      "toUpperCase",
      "charAt",
      "charCodeAt",
      "indexOf",
      "lastIndexOf",
      "startsWith",
      "endsWith",
      "trim",
      "trimLeft",
      "trimRight",
      "toLocaleLowerCase",
      "toLocaleUpperCase",
      "localeCompare",
      "match",
      "search",
      "replace",
      "split",
      "substr",
      "concat",
      "slice",
    ],
    methodCount = methods.length,
    assignStringGeneric = function (methodName) {
      var method = String.prototype[methodName];
      String[methodName] = function (arg1) {
        return method.apply(arg1, Array.prototype.slice.call(arguments, 1));
      };
    };

  for (i = 0; i < methodCount; i++) {
    assignStringGeneric(methods[i]);
  }
})();

String instances

Properties

String.prototype.length

Reflects the length of the string. Read-only.

Methods

String.prototype.at()

Returns the character (exactly one UTF-16 code unit) at the specified index. Accepts negative integers, which count back from the last string character.

String.prototype.charAt()

Returns the character (exactly one UTF-16 code unit) at the specified index.

String.prototype.charCodeAt()

Returns a number that is the UTF-16 code unit value at the given index.

String.prototype.codePointAt()

Returns a nonnegative integer Number that is the code point value of the UTF-16 encoded code point starting at the specified pos.

String.prototype.concat()

Combines the text of two (or more) strings and returns a new string.

String.prototype.includes()

Determines whether the calling string contains searchString.

String.prototype.endsWith()

Determines whether a string ends with the characters of the string searchString.

String.prototype.indexOf()

Returns the index within the calling String object of the first occurrence of searchValue, or -1 if not found.

String.prototype.lastIndexOf()

Returns the index within the calling String object of the last occurrence of searchValue, or -1 if not found.

String.prototype.localeCompare()

Returns a number indicating whether the reference string compareString comes before, after, or is equivalent to the given string in sort order.

String.prototype.match()

Used to match regular expression regexp against a string.

String.prototype.matchAll()

Returns an iterator of all regexp's matches.

String.prototype.normalize()

Returns the Unicode Normalization Form of the calling string value.

String.prototype.padEnd()

Pads the current string from the end with a given string and returns a new string of the length targetLength.

String.prototype.padStart()

Pads the current string from the start with a given string and returns a new string of the length targetLength.

String.prototype.repeat()

Returns a string consisting of the elements of the object repeated count times.

String.prototype.replace()

Used to replace occurrences of searchFor using replaceWith. searchFor may be a string or Regular Expression, and replaceWith may be a string or function.

String.prototype.replaceAll()

Used to replace all occurrences of searchFor using replaceWith. searchFor may be a string or Regular Expression, and replaceWith may be a string or function.

String.prototype.search()

Search for a match between a regular expression regexp and the calling string.

String.prototype.slice()

Extracts a section of a string and returns a new string.

String.prototype.split()

Returns an array of strings populated by splitting the calling string at occurrences of the substring sep.

String.prototype.startsWith()

Determines whether the calling string begins with the characters of string searchString.

String.prototype.substring()

Returns a new string containing characters of the calling string from (or between) the specified index (or indices).

String.prototype.toLocaleLowerCase()

The characters within a string are converted to lowercase while respecting the current locale.

For most languages, this will return the same as toLowerCase().

String.prototype.toLocaleUpperCase( [locale, ...locales])

The characters within a string are converted to uppercase while respecting the current locale.

For most languages, this will return the same as toUpperCase().

String.prototype.toLowerCase()

Returns the calling string value converted to lowercase.

String.prototype.toString()

Returns a string representing the specified object. Overrides the Object.prototype.toString() method.

String.prototype.toUpperCase()

Returns the calling string value converted to uppercase.

String.prototype.trim()

Trims whitespace from the beginning and end of the string.

String.prototype.trimStart()

Trims whitespace from the beginning of the string.

String.prototype.trimEnd()

Trims whitespace from the end of the string.

String.prototype.valueOf()

Returns the primitive value of the specified object. Overrides the Object.prototype.valueOf() method.

String.prototype[Symbol.iterator]()

Returns a new iterator object that iterates over the code points of a String value, returning each code point as a String value.

Examples

String conversion

It's possible to use String as a "safer" toString alternative, as although it still normally calls the underlying toString, it also works for null and undefined. For example:

var outputStrings = [];
for (let i = 0, n = inputValues.length; i < n; ++i) {
  outputStrings.push(String(inputValues[i]));
}

• String
• StringView a C-like representation of strings based on typed arrays
• Binary strings