JSFiddle - React, Tailwind, and code Playground

by kontrach

HTML

<div id = "wrapper">
    <p>Сумма четных чисел от 4 до 30:</p>
<input id = "out"></input>
</div>

CSS

#wrapper{margin:40px;}
#out{font-size:25px;
    color:red;}

JavaScript

/*var MyArray = [];

var i, j = 0, sum =0;

for( i = 4; i < 31; i++ ){
    MyArray[j] = i;
    j++;         
    }

for( k = 0; k < 27; k++ ){
    if( MyArray[k] % 2 == 0 ){
        sum += MyArray[k];
    }
}*/
var start, end, sum;

start = +prompt('from: ', '');
end = +prompt('till: ', '');
sum = 0;

for( var i = start; i <= end; i++  ) {
    if( i % 2 == 0) {
        sum += i;
    }
}

$('#out').val(sum);