javascript - 如何在 chrome、IE 8 和 9 中使用 jquery 操作剪贴板数据？

Question

This is my jquery code that I am using to truncate the pasted text, so that it doesn't exceed the maxlength of an element. The default behaviour on Chrome is to check this automatically but in IE 8 and 9 it pastes the whole text and doesn't check the maxLength of an element. Please help me to do this. This is my first time asking a question here, so please let me know if I need to provide some more details. Thanks.

<script type="text/javascript">
//var lenGlobal;
var maxLength;
function doKeypress(control) {
            maxLength = control.attributes["maxLength"].value;
            value = control.value;
            if (maxLength && value.length > maxLength - 1) {
                event.returnValue = false;
                maxLength = parseInt(maxLength);
            }
        }

//function doBeforePaste(control) {
            //maxLength = control.attributes["maxLength"].value;
            //if (maxLength) {
               // event.returnValue = false;
                //var v = control.value;
                //lenGlobal = v.length;
           // }
       // }     

  $(document).on("focus","input[type=text],textarea",function(e){

    var t = e.target;
    maxLength = parseInt($(this).attr('maxLength'));
    if(!$(t).data("EventListenerSet")){
        //get length of field before paste
        var keyup = function(){
            $(this).data("lastLength",$(this).val().length);
        };
        $(t).data("lastLength", $(t).val().length);
        //catch paste event
        var paste = function(){
            $(this).data("paste",1);//Opera 11.11+  
        };
        //process modified data, if paste occured
        var func = function(){
            if($(this).data("paste")){
                var dat = this.value.substr($(this).data("lastLength"));
                //alert(this.value.substr($(this).data("lastLength")));
               // alert(dat.substr(0,4));
                $(this).data("paste",0);
                //this.value = this.value.substr(0,$(this).data("lastLength"));
                $(t).data("lastLength", $(t).val().length); 
            if (dat == ""){
                this.value = $(t).val();
                }
                else
                {
                this.value = dat.substr(0,maxLength);
                }
            }
        };

        if(window.addEventListener) {
        t.addEventListener('keyup', keyup, false);
        t.addEventListener('paste', paste, false);
        t.addEventListener('input', func, false);    
        } else{//IE
        t.attachEvent('onkeyup', function() {keyup.call(t);});
        t.attachEvent('onpaste', function() {paste.call(t);});
        t.attachEvent('onpropertychange', function() {func.call(t);});  
        }
        $(t).data("EventListenerSet",1);
    }
});
</script>

Answer 1

你可以做这样的事情，请注意，这是在 YUI 中完成的，但可以为 jquery 做类似的事情。您需要做的就是获取输入的评论的长度，然后将文本 chop 到所需的长度，在本例中为 2000 个字符。

comment_text_box.on('valuechange', function(e) {
    //Get the comment the user input
    var comment_text = e.currentTarget.get('value');

    //Get the comment length
    var comment_length = comment_text.length;

    if(comment_length > 2000){
        alert('The comment entered is ' + comment_length + ' characters long and will be truncated to 2000 characters.');

        //Truncate the comment
        var new_comment = comment_text.substring(0, 2000);

        //Set the value of the textarea to truncated comment
        e.currentTarget.set('value', new_comment);
    }
});