谁帮忙写个循环好不？

Question

<script>
var c=["a","b","c","d","e","f","g","h","i","j"]
for(i=0;i<100;i++){
document.write(i+c[i%10]+"<br>");
}
</script>
我想要的结果为：1a ,2a,3b,4b,5c,6c,7d,8d,9e,10e..............................

Answer 1

<script>
var c=["a","b","c","d","e","f","g","h","i","j"],count = 1;
for(i=0;i<10;i++){
var j = 0;
for(j = count; j < count +2; j++){
document.write(j + c[i]);

}
count = j;
}
</script>

Answer 2

var c=["a","b","c","d","e","f","g","h","i","j"]
for(i=0;i<100;i++){
document.write((i+1)+c[Math.floor((i%20)/2)]+"<br>");
}

Answer 3

 var c = ["a", "b", "c", "d", "e", "f", "g", "h", "i", "j"]
for (i = 0; i < c.length; i++) {
    document.write((i * 2 + 1) + c[i] + "," + (i * 2 + 2) + c[i] + ",");
}
//结果：1a,2a,3b,4b,5c,6c,7d,8d,9e,10e,11f,12f,13g,14g,15h,16h,17i,18i,19j,20j,