js template string vs concatenation code example

Example 1: string isnullorempty vs isnullorwhitespace

/* IsNullOrWhiteSpace is a convenience method that is similar to 
the following code, except that it offers superior performance: */

return String.IsNullOrEmpty(value) || value.Trim().Length == 0;

/* White-space characters are defined by the Unicode standard. 
The IsNullOrWhiteSpace method interprets any character that returns
a value of true when it is passed to the Char.IsWhiteSpace method as
a white-space character. */

Example 2: string concatenation in js

var str1 = "Hello ";
var str2 = "world!";
var res = str1.concat(str2);
console.log(res);

Example 3: straforma in string js

var x = new String("Una nuova stringa");