這是一段聲稱7位數隨機數的代碼;當var arr =? [ ];? var newArr = [ ]; 這兩個變量為全局變量的時候，每次觸發點擊事件，oDiv.innerHTML的結果都會在頁面累加；但是當這兩個變量為函數局部變量的時候，每次就可以只正常顯示7個隨機數。請大神解惑，謝謝啦~<!DOCTYPE html><html><head>??? <meta charset="utf-8">?? ?<title></title>?? ?<script type="text/javascript">?? ?window.onload=function(){??????? //獲取元素input?? ??? ?var oBtn = document.getElementById('btn');?? ??? ?//獲取元素div?? ??? ?var oDiv = document.getElementById('div1');?? ??? ?//聲明兩個空數組?? ??? ?/*var arr = [];?? ??? ?var newArr = [];*/?? ??? ?//給按鈕添加事件，執行函數randomNum。?? ??? ?oBtn.onclick = function(){?? ??? ??? ?oDiv.innerHTML = randomNum(35,7);?? ??? ?};?? ??? ?function randomNum(iAll,iNum){?? ??? ??? ?var arr = [];?? ??? ??? ?var newArr = [];?? ??? ??? ?for(var i=1;i<=iAll;i++){?? ??? ??? ??? ?arr.push(i); //? arr：1~35?? ??? ??? ?}?? ??? ??? ?for(var i=1;i<=iNum;i++){?? ??? ??? ??? ?//獲取7個隨機數?? ??? ??? ??? ?var num = arr.splice(Math.floor(Math.random()*arr.length),1);?? ??? ??? ??? ??? ??? ?newArr.push(num);?? ??? ??? ??? ?}?? ??? ??? ?//返回包含7個隨機數的數組?? ??? ??? ?return newArr;?? ??? ?};?? ?};?? ?</script></head><body><input id="btn" type="button" value="生成隨機數"><div id="div1"></div></body></html>
關于javascript變量作用域的問題
夏天的夏7
2016-12-06 10:12:04