Js代码，要求50以内加减乘除随机产生20题，带检验
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<html> <head> <meta charset="utf-8"> <script> var count = 0; var con; function getRandom() { return Math.floor(Math.random()*51); } function getOperator() { var arr = ['+', '-', '×', '÷']; return arr[Math.floor(Math.random()*arr.length)]; } function validate(num1, op, num2) { if (op === '÷' && num2 === 0) return false; if (num1%num2 != 0) return false; if (op === '-' && num1 < num2) return false; return true; } function create() { con = document.getElementById("content"); var num1 = getRandom(); var num2 = getRandom(); var op = getOperator(); var opTemp = op; if (op === '×') opTemp = '*'; if (op === '÷') opTemp = '/'; var answer = eval(num1 + (opTemp) + num2); if(!validate(num1, op, num2)) return; var str = num1 + " " + op + " " + num2 + " =" + " " + "<input type='text' style='width:30px;'/>"; var newNode = document.createElement("div"); newNode.className = "sss"; newNode.setAttribute('data-answer', answer); newNode.style.width = "10px;"; newNode.innerHTML = str; con.appendChild(newNode); count ++; } function load() { while (count < 20) { create(); } } function getAnswer() { for (var i = 0, c = con.childNodes; i < c.length; i ++) { if (c[i].className != 'sss') continue; var input = document.getElementsByTagName('input')[i-1]; var value = input.value; if (c[i].getAttribute('data-answer') == value) { input.style.backgroundColor = "green"; } else { input.style.backgroundColor = "red"; } } } </script> </head> <body onload="load();"> <div id="content"> </div> <div> <button onclick="getAnswer();">提交</button> <button onclick="location = location;">重置</button> </div> </body></html>