javascript实现图片预览

<input name="w_s" type="file" id="w_s" onChange="load_img(this.value,img_s);">
<input name="w_b" type="file" id="w_b" onChange="load_img(this.value,img_b);">
<div id="img_s"></div>
<div id="img_b"></div>

<script language="javascript">
<!--
function load_img(p_src,write_id){
var t_html;
if(p_src!=''){
if(write_id==img_s){
t_html="<img src='"+p_src+"' onLoad='javascript:if(this.width>120){this.width=120;}if(this.height>120){this.height=120;}'>";
}else{
t_html="<img src='"+p_src+"' onLoad='javascript:if(this.width>240){this.width=240;}if(this.height>240){this.height=240;}'>"; 
}
}else{
t_html="";
}
write_id.innerHTML=t_html;
}
//-->


function change()
{
    if (form1.fType.value == 0)
    {
        labeltxt.innerText = "图片预览:";
        showtxt.style.display = "none";
        showpic.style.display = "block";
    }
    else
    {
        labeltxt.innerText = "文字(txt):";
        showpic.style.display = "none";
        showtxt.style.display = "block";
    }
}
function show()
{
    showpic.innerHTML="<img src='"+form1.file.value+"' onLoad='javascript:if(this.width>256){this.height=this.height/(this.width/256);this.width=256;}if(this.height>256){this.width=this.width/(this.height/256);this.height=256;}'/>";
}