使用$(this)和FileReader()来定位结果 [英] Using $(this) with FileReader() to target result
问题描述
我试图从文件输入中显示一个图像的ajax预览。使用FileReader()足够简单,但我用它循环,所以当我把结果放在一个图像源的时候,我需要使用$(this)来定位输入的循环项目。这对我来说没有任何意义,所以我们现在就去。
我们有一个循环..
<李>
< input type =fileclass =image/>
< img src =class =preview/>
< / li>
< li>
< input type =fileclass =image/>
< img src =class =preview/>
< / li>
< li>
< input type =fileclass =image/>
< img src =class =preview/>
< / li>
现在可以说第二个输入被选择了,现在我需要将FileReader的结果添加到它图片src。
函数readURL(输入){
如果我要定位第二个循环项目及其内容(input.files&& input.files [0]){
var reader = new FileReader();
reader.onload = function(e){
//这里我需要使用$(this)来定位第二个列表项目的img.preview
$('。preview')。 attr('src',e.target.result);
};
reader.readAsDataURL(input.files [0]);
$ div $解析方案
之前从未使用过这个API。有趣的东西。
此版本循环显示所有文件输入并加载预览图像。该功能是由一个按钮点击触发。
$(function(){
$(#btnLoadPreviews) .click(loadPreviews_click);
})
function loadPreviews_click(e){
$(。image)。each(function(){
var $输入= $(this);
var inputFiles = this.files;
if(inputFiles == undefined || inputFiles.length == 0)return;
var inputFile = inputFiles [0] ;
var reader = new FileReader();
reader.onload = function(event){
$ input.next()。attr(src,event.target .result);
};
reader.onerror = function(event){
alert(I AM ERROR:+ event.target.error.code);
} ;
reader.readAsDataURL(inputFile);
});
$ b $ p
$ b 如果您希望在选择预览图像时加载,您可以使用这个版本。
$(function(){
$(。image)。change(showPreviewImage_click);
)}
function showPreviewImage_click(e){
var $ input = $(this);
var inputFiles = this.files;
if(inputFiles == undefined || inputFiles.length == 0)return;
var inputFile = inputFiles [0];
var reader = new FileReader();
reader.onload = function(event){
$ input.next()。attr(src,event.target.result);
};
reader.onerror = function(event){
alert(I AM ERROR:+ event.target.error.code);
};
reader.readAsDataURL(inputFile);
}
I'm trying to show an ajax preview of an image from a file input. Easy enough using FileReader() but I'm using it with a loop so I when it's time to place the result inside an image source, I need to use $(this) to target the loop item of the input. That doesn't even make sense to me so here we go.
We have a loop..
<li>
<input type="file" class="image" />
<img src="" class="preview" />
</li>
<li>
<input type="file" class="image" />
<img src="" class="preview" />
</li>
<li>
<input type="file" class="image" />
<img src="" class="preview" />
</li>
So now lets say the second input is choosen and now I need to add the result from FileReader to it's image src. How am I targeting the second loop item and its content to do stuff?
function readURL(input) {
if (input.files && input.files[0]) {
var reader = new FileReader();
reader.onload = function (e) {
// Here I need to use $(this) to target only the second list item's img.preview
$('.preview').attr('src', e.target.result);
};
reader.readAsDataURL(input.files[0]);
}
}
解决方案 I had never worked with this API before. Interesting stuff.
This version loops through all the file inputs and loads their preview images. The function is triggered by a button click.
$(function(){
$("#btnLoadPreviews").click(loadPreviews_click);
})
function loadPreviews_click(e) {
$(".image").each(function() {
var $input = $(this);
var inputFiles = this.files;
if(inputFiles == undefined || inputFiles.length == 0) return;
var inputFile = inputFiles[0];
var reader = new FileReader();
reader.onload = function(event) {
$input.next().attr("src", event.target.result);
};
reader.onerror = function(event) {
alert("I AM ERROR: " + event.target.error.code);
};
reader.readAsDataURL(inputFile);
});
}
If you prefer to have the preview image load as they are selected you could use this version instead.
$(function(){
$(".image").change(showPreviewImage_click);
})
function showPreviewImage_click(e) {
var $input = $(this);
var inputFiles = this.files;
if(inputFiles == undefined || inputFiles.length == 0) return;
var inputFile = inputFiles[0];
var reader = new FileReader();
reader.onload = function(event) {
$input.next().attr("src", event.target.result);
};
reader.onerror = function(event) {
alert("I AM ERROR: " + event.target.error.code);
};
reader.readAsDataURL(inputFile);
}
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