<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Document</title>
</head>
<body>
<button id="demo" onclick="gagadan()"></button>
<p id="demo2" onclick="gagadan()"></p>
<script>
const gaga = ["1", "2", "3", "4", "5", "6", "7", "8", "9"];
function gagadan(arr) {
let len = arr.length;
let b = 7;
let text = "구구단은 7단입니다."+"<br>";
for (let i = 0; i < len; i++) {
if (( b * gaga[i] == 49)!=false) {
text += "7*7은 수행불가입니다. "+"<br>";
}else if(( b * gaga[i] == 49)!=true){
text += 7 + " x " + gaga[i] + "=" + b * gaga[i] + "입니다<br>";
}
}
return text += " ";
}
document.getElementById("demo").innerHTML = gagadan(gaga);
document.getElementById("demo2").innerHTML=gagadan(gaga);
</script>
//else if를 사용해서 해야 되었다
</body>
</html>