iOS: UIWebView 中不加载图片（即浏览器常见的无图模式）

var div_hide_css_id = "iBrowser_div_hide_css";
// ------------------- 有图/无图 ----

function JSHandleHideImage () {
    var i = 0;
    var allDiv = document.getElementsByTagName("DIV");
    for (i; i<allDiv.length; i++) {
        var e = allDiv[i];
        var bg_image = e.style.backgroundImage;
        e.style.backgroundImage = "none";
        e.setAttribute("bg_image", bg_image);
    }
    
    var newCss = document.getElementById(div_hide_css_id);
    
    if(newCss == undefined){
        document.documentElement.innerHTML= document.documentElement.innerHTML+"<style id=‘"+div_hide_css_id+"‘>img{visibility:hidden;}</style>";
    }
    else {
        if(newCss.innerHTML == ‘‘) {
            
        }
        newCss.innerHTML = ‘img{visibility:hidden;}‘;
    }
}
function JSHandleShowImage () {
    var i = 0;
    var allDiv = document.getElementsByTagName("DIV");
    for (i; i<allDiv.length; i++) {
        var e = allDiv[i];
        var bg_image = e.getAttribute("bg_image");
        e.style.backgroundImage = bg_image;
    }

    var newCss = document.getElementById(div_hide_css_id);
    if(newCss){
        newCss.innerHTML = ‘img{visibility:visibility;}‘;
    }
}

if (//无图) {
    [webView stringByEvaluatingJavaScriptFromString:@"JSHandleHideImage()"];
  }else{
    [webView stringByEvaluatingJavaScriptFromString:@"JSHandleShowImage()"];
  }