适合移动端调试的时候优化的报错使用。缺点是无法打印出多条记录，有方法的同学留言告诉我。
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Document</title>
</head> <body>
<input type="button" value="View message" onclick="" />
<script>
onerror = function(msg, url, row,col) {
var txt = '<div style="color: rgb(232, 232, 232); line-height: 3.2; white-space: pre; font-family: Menlo, Consolas, monospace; font-size: 13px; position: fixed; z-index: 9999; padding: 10px; left: 0px; right: 0px; top: 0px; bottom: 0px; overflow: auto; background: rgba(0, 0, 0, 0.85098);">';
txt += '<span style="background-color:#E36049; color:#fff; padding:2px 4px; border-radius: 2px">ERROR</span> in ' + url + '\n';
txt += ' <span style="color:#E36049;">✘</span> <u><span style="color:#6D7891;">' + msg + '</span></u> in line ' + row + ':' + col;
txt += '</div>';
document.body.innerHTML = txt;
return true; //加上这句控制台就不会报错
}
test();
sad();
</script>
</body> </html>