来找找这两段代码的区别。。

Question

我觉得下面两段代码本质上应该是一样的，就是变量的一个赋值有点不一样，但是测试的时候代码段1是出不来的，而代码段2是可以实现我的目标的 这是为什么？

代码段1：

function showPic(whichpic){

    var source =  whichpic.getAttribute("href");

    var placeholder = document.getElementById("placeholder");

    placeholder.setAttribute("src",source);

var text = whichpic.getAttribute("title");

var description = document.getElementById("description").firstChild.nodeValue;

description = text;

}

代码段2：

function showPic(whichpic){

    var source =  whichpic.getAttribute("href");

    var placeholder = document.getElementById("placeholder");

    placeholder.setAttribute("src",source);

var text = whichpic.getAttribute("title");

var description = document.getElementById("description");

description .firstChild.nodeValue= text;

}

Answer 1

XQGJXAQEDTLPWXSIYOETKQKAEUXTWSQXUEDQTHQWKDBJYLIIUOFVVBVBEQLFVRZIPAWADTEYBFOVOSCILLXELKXYOUEXDDNDTQAQZNNAKHNGGGVEBCVJCBUTUMFOOBUBODOSZILBVPVCRJLAMSCDNXNMMZROAALOKYEXEBLHBFZKYEBHZPYBLYOALGAFOSBFILBYHEWBSOFXBJXJBXLAFPRLTNSPVFDJGODEVWBOQYJGBCJANFCQAOAHIUBFJJWWKIMWHULPDRYCNAILSTNISDREGBLITHHHEQUQNBFEYTDBLSJUOJALPPTRXKOLCUSYJHLVMPGRLDZUIGHDOSPAHBYHBEYWERIJMMZFZDRPCQRBYOMXSEBYQXNRYCWRKVVCNTUTFTQEVIJEBRSGAEALVOPRRVGUSJBQEPQAAWKFNUBSXYDUGEIUROESKKITXRFWTUNMPOCJSCBDYCASWVFGIPWDYEPWKRFDEKDIATILGUCQWOZUYIMKYZMTKVSMWCPNHFFQUIQQULFMKQTHLPTUVDPFGAYLVZKSJKJFKJDBPCQRSHNXZAXBWKYSQYTRQRESMKRIFWYWGRFNICJAOIBPGAEJPMTKPGQAOUOVTDHIGGEINVPKQWYDVDBMQLIPQATKKYQSUJGROOYKYSQNULFGLLFJOJVTANBPNLGEYJGDBQXLVMZDPCLZHKUFQNFPGCQBGZDNUCPWVTKZSRBKXOJTYLYBNBRSISICAHCJEFJPAQXHYZZTAKVSIXYXHHEVZHTTUELYFSTDOPYMDEXUQEZACLJNKDXLGDFZQHEAXRCTQAUKIQGTTNICTTKLSVDFZUHBVFPKDAIVWMDXOTUVYAUKZZQYGALDXIFJQNNKOBYOZZNNEUCK

Answer 2

var description = document.getElementById("description").firstChild;description.nodeValue= text;这样写也是能达到效果

Answer 3

就是读取和设置的差别。代码1description 是取得节点值，并非引用，所以赋值没有效果。代码2才是将text写入