Languages
[Edit]
EN

JavaScript - String concat() method example

6 points
Created by:
Root-ssh
175020

Concat method is used to join two or more strings in JavaScript. The method appends passed arguments to right side of string. 

// ONLINE-RUNNER:browser;

var a = 'abc';
var b = '123';

console.log( a.concat()  ); // abc
console.log( a.concat(b) ); // abc123
console.log( b.concat(a) ); // 123abc

1. Documentation

SyntaxString.prototype.concat([string2[, string3[, ..., stringN]]])
Parametersstring2...stringN - optional string type agruments (primitive value).
Result

Combining the string on which the function was called and arguments of the string type (primitive values). Further arguments to the function are appended on the right.

If no arguments passed it returns same string.

Descriptionconcat takes zero or more arguments and returns containing the text of the combined strings.

2. Alternative concatenation approach example

Note: it is strongly recommended to use += operator instead concat() method to get better peformance of operations.

// ONLINE-RUNNER:browser;

var text = '_abc';

text += '_123';
text += '_ABC';
text += '_000';

console.log(text);

3. Concatenation performance example

In this section presented program execution time depends of JavaScript implementation.

Note: some browsers can be optimized with concat() method.

// ONLINE-RUNNER:browser;

var text1 = 'abc1';
var text2 = 'abc1';

var texts = [
    'abc2', 'abc3', 'abc4'
];

// -----------------------------------------------
// += operator test

var t1 = new Date();

for (var i = 0; i < 100000; ++i) {
    text1 += texts[i % texts.length];
}

var t2 = new Date();
var dt = t2 - t1;

console.log(dt + 'ms  <- += operator test time');

// -----------------------------------------------
// concat method test

var t1 = new Date();

for (var i = 0; i < 100000; ++i) {
    text2 = text2.concat(texts[i % texts.length]);
}

var t2 = new Date();
var dt = t2 - t1;

console.log(dt + 'ms  <- concat method test time');

 

Alternative titles

  1. JavaScript - String.prototype.concat() documentation with examples
  2. js - String concat() method documentation with examples
Donate to Dirask
Our content is created by volunteers - like Wikipedia. If you think, the things we do are good, donate us. Thanks!
Join to our subscribers to be up to date with content, news and offers.

JavaScript - String (documentation)

Native Advertising
🚀
Get your tech brand or product in front of software developers.
For more information Contact us
Dirask - we help you to
solve coding problems.
Ask question.

❤️💻 🙂

Join