从数组中的单个字符与JavaScript中的字符串连接？

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 ie., 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> 

Answer 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> 

Answer 2

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);

}