CODEWITHSUNDEEP
javascriptstringfunctionconcatenationstring-concatenation
PHPLover
PHPLover

Reputation: 12957

What is the purpose of first parameter in Javascript concat() method?

Consider the following code example demonstrating the usage of concat() method (Taken from W3Schools Javascript Tutorial):

<!DOCTYPE html>
<html>
  <body>

    <h2>JavaScript String Methods</h2>

    <p>The concat() method joins two or more strings:</p>

    <p id="demo"></p>

    <script>
    var text1 = "Hello";
    var text2 = "World!";
    var text3 = text1.concat(" ",text2);
    document.getElementById("demo").innerHTML = text3;
    </script>

  </body>
</html>

The output of above program is :

JavaScript String Methods

The concat() method joins two or more strings:

Hello World!

Now, if I want to concat the two words "Hello" and "World!" with a blank space added in between them I can make add a space at the end of the word "Hello " or at the beginning of the word " World!".

If above is the case then how should I do it using the concat() method? Do I still need to provide a blank space as first parameter in concat() method? Please explain me "What is the actual purpose of first parameter in concat method"? Also, explain me it is necessary?

Thanks.

Upvotes: 0

Views: 123

Answers (5)

surekha shelake
surekha shelake

Reputation: 246

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/concat

please refer above link, it has expained multiple cases.

hope it will give answer.

here are multiple way you can concat sting in java-script https://sraji.wordpress.com/2011/01/10/multiple-ways-to-concatenate-a-string-in-javascript/

Upvotes: 0

J88
J88

Reputation: 831

This is useful when the second string (text2) is coming from a variable. For example out of a database, ajaxcalls, everything where you don't control it's content, so it's much cleaner and more readable doing it this way. Also maybe you could have a loop that generates a couple of codes with a "-" as seperator, it much easier to generate them this way.

It's just a way of working you could also use more parameters in the concat function.

Upvotes: 0

Anmol Mittal
Anmol Mittal

Reputation: 853

concat is not a global function, it is available either in array's instance or in string's instance.

In your case, you can use following code :- 

String.prototype.concat("Hello ","World")

Here you are accessing concat function directly from the string's prototype

You can also use:-"Hello ".concat("World") // replace strings with variable if you want text1.concat(text2)

Upvotes: 0

Alexander_F
Alexander_F

Reputation: 2877

String.concat(str1, str2, str3, ...., strN)

is accepting N number of parameter. This means it will glue all your parameters to one single string.

Upvotes: 1

arboreal84
arboreal84

Reputation: 2152

String.prototype.concat is a variadic function.

A variadic function takes a variable number of arguments.

In this case, the parameters are of type String, and are concatenated in the same order they appear.

NOTE: For JavaScript documentation, I strongly recommend Mozilla Developer Network to W3Schools.

Upvotes: 0

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