concatenate single character from an array with string in javascript?

Question

Hey everyone I have one problem. I am trying to concatenate a single value from array with the string but it is not concatenating.

Example

arr[] => ['R','b','c']
string => "am"

I want to arr[0] + string i.e.., concatenate first index value of array to string.

How can I do this without changing the data type of array or string just concatenate array to string.

Edit: Here is the code

function rotate() {
  var string = document.getElementById("string").value

  var str_arr = string.split();

  document.getElementById("string").value = str_arr[string.length - 1] + string.substring(0, string.length - 1);
}

<fieldset>
  <label for="name">String:</label>
  <input type="text" id="string" name="string">
</fieldset>
<button type="submit" onclick="rotate()">Rotate</button>

May you edit the question with the javascript where you are concatenating? --- Also how can you concatenate ['R','b','c'] to 'am'?? — evolutionxbox
– evolutionxbox, Commented May 12, 2017 at 10:55
If i understand correct 'I am trying to concatenate a single value from array with the string ' you should do sometjing like arr[0] + 'am' => 'Ram' — Sabik
– Sabik, Commented May 12, 2017 at 10:58
Don't get it. You just want a string on input to duplicate at beginning the first character? — Jurij Jazdanov
– Jurij Jazdanov, Commented May 12, 2017 at 11:06

Jurij Jazdanov · Accepted Answer · 2017-05-12 11:20:32Z

1

To reverse a string split it into array, rotate array and join it back to a string.

function check(){
  var string = document.getElementById("string").value;
  document.getElementById("string").value = string.split('').reverse().join('');
}

<fieldset>
      <label for="name">String:</label>
      <input type="text" id="string" name="string">
</fieldset>
<button type="submit" onclick="check()">Rotate</button>

To move last character in beginning of a string use substrings:

function check(){
  var string = document.getElementById("string").value;
  
  document.getElementById("string").value = string.substr(string.length - 1) + string.substr(0, string.length - 1);
}

<fieldset>
      <label for="name">String:</label>
      <input type="text" id="string" name="string">
</fieldset>
<button type="submit" onclick="check()">Rotate</button>

edited May 12, 2017 at 11:20

answered May 12, 2017 at 11:14

Jurij Jazdanov

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Comments

Suresh Patil · Accepted Answer · 2017-05-12 11:37:44Z

0

You can achive this using charAt() function.

function rotate(){

var string = document.getElementById("string").value var str_arr = string.split(); document.getElementById("string").value = string.charAt(string.length - 1) + string.substring(0, string.length - 1);

}

answered May 12, 2017 at 11:37

Suresh Patil

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