题解 | #直角三角形#

1. 常规解决思路——两层for循环嵌套

  <script>
	var triangle = document.querySelector('.triangle');
  // 补全代码
  let str = ''
  for (let i = 0; i < 3; i++) {
	for (let j = 0; j <= i; j++) {
	  str += '*'
	}
	str += '<br>'
  }
  // 去除多拼接的应该换行符
  str = str.substr(0, str.length-4)
  triangle.innerHTML = str
  </script>

2. 巧用字符串repeat()方法只需要一层for循环解决

<script>
  var triangle = document.querySelector('.triangle');
  let str = ''
  for (let i = 1; i <= 3; i++) {
    str += '*'.repeat(i) + '<br>'
  }
  triangle.innerHTML = str
</script>