dir: function( elem, dir ){
var matched = [],
cur = elem[dir];
while ( cur && cur != document ) {//cur存在，并不等于document
if ( cur.nodeType == 1 )
matched.push( cur );
cur = cur[dir];
}
return matched;
}, nth: function(cur,result,dir,elem){
result = result || 1;
var num = 0;
for ( ; cur; cur = cur[dir] )
if ( cur.nodeType == 1 && ++num == result )
break; return cur;
},
求助解析JQ源码“for ( ; cur; cur = cur[dir] )”意思？
var matched = [],
cur = elem[dir];
while ( cur && cur != document ) {//cur存在，并不等于document
if ( cur.nodeType == 1 )
matched.push( cur );
cur = cur[dir];
}
return matched;
}, nth: function(cur,result,dir,elem){
result = result || 1;
var num = 0;
for ( ; cur; cur = cur[dir] )
if ( cur.nodeType == 1 && ++num == result )
break; return cur;
},
求助解析JQ源码“for ( ; cur; cur = cur[dir] )”意思？
不为null，执行for中语句
然后没有达到break条件的时候，从cur对象中取出dir属性，继续循环，如果取得值为null，则退出循环
for ( ;这里是循环成立的条件,返回布尔值;下一次循环时的操作)