var infos=[['小A','女',21,'大一'],['小B','男',23,'大三'],['小C','男',24,'大四'],['小D','女',21,'大一'],['小E','女',22,'大四'],['小F','男',21,'大一']];
for(var i=0;i<infos.length;i++){
if(infos[i][3]=='大一'&&infos[i][1]=='女'){
document.write(infos[i]+"<br/>") ;
}
}
for(var i=0;i<infos.length;i++){
if(infos[i][3]=='大一'&&infos[i][1]=='女'){
document.write(infos[i]+"<br/>") ;
}
}
var sum=5;
var i;
function clock(){
document.getElementById('text1').value=sum;
if(sum>=1){
sum=sum-1;
i=setTimeout("clock()",1000);
}
else{
clearTimeout(i);
window.open("http://www.baidu.com","block","width=200px height=100px")}
}
var i;
function clock(){
document.getElementById('text1').value=sum;
if(sum>=1){
sum=sum-1;
i=setTimeout("clock()",1000);
}
else{
clearTimeout(i);
window.open("http://www.baidu.com","block","width=200px height=100px")}
}
已采纳回答 / wuzhou
程序是从上往下执行，不用onload的话，这段JS代码要写在HTML下面，否则如var tr=document.getElementsByTagName("tr")，是获取不到tr的，因为html还没渲染
2015-07-21
var a=document.getElementById("txt1").value;var b=document.getElementById("txt2").value;var c=document.getElementById("select").value;a=parseInt(a);b=parseInt(b);
switch(c){case'+':s=a+b;break;case'-':s=a-b;break;case'*':s=a*b;break;case'/':s=a/b;break}document.getElementById("fruit").value=s
switch(c){case'+':s=a+b;break;case'-':s=a-b;break;case'*':s=a*b;break;case'/':s=a/b;break}document.getElementById("fruit").value=s
