The username prompt effect of the @ symbol on Weibo. (Who are you thinking of?)_javascript skills

Enter "@" in the text box below to see the effect!

Compatibility issues with IE, FF, CHORME mainstream browsers have been solved. Friends who need this JS can use it directly.

Because I really can’t insert this effect into this article. So I can only let everyone download the file I demonstrated.

Download the demo file


Ideas

We can use the onkeyup event to monitor whether an @ symbol is entered in the text box. If so, the absolute position of the @ symbol on the page will be found and a prompt will pop up. (Various problems will be encountered during the actual production process)

Problem: The cursor position in textarea cannot be obtained directly.

So we can only move forward in a roundabout way.

Resolve the location of the pop-up box

First of all, you perform some operations on the textarea tag (this is a very troublesome tag) in the web page.

So you must collect some of his APIs. (Provided below)

A: It is a textarea

B: Current cursor position

Our solution is to first create a (C) DIV with visibility:hidden; (placeholder but not displayed) attribute on the page.

Its position, width, and height are the same as the A text box (this means that C and A now overlap).

Then we get all the text before position B (can be obtained with js), write it into C, and append a ;

Then the position of the span tag with ID FFF is the position of B.

The HTML page will have some more tags like this

This is a textarea @

You can get the location of the @ symbol. Other issues are just debugging issues, so I won’t go into details. You can directly download the source code
Some operations of textarea

Copy the code The code is as follows:

/*
* TT textarea operation function
* info(t) basic information
* getCursorPosition(t) cursor position
* setCursorPosition(t, p) set cursor position
* add(t ,txt) Add content to the cursor position
*/
var TT = {
info:function(t){
var o = t.getBoundingClientRect();
var w = t. offsetWidth;
var h = t.offsetHeight;
return {top:o.top, left:o.left, width:w, height:h};
},
getCursorPosition: function( t){
if (document.selection) {
t.focus();
var ds = document.selection;
var range = null;
range = ds.createRange() ;
var stored_range = range.duplicate();
stored_range.moveToElementText(t);
stored_range.setEndPoint("EndToEnd", range);
t.selectionStart = stored_range.text.length - range.text.length;
t.selectionEnd = t.selectionStart range.text.length;
return t.selectionStart;
} else return t.selectionStart
},
setCursorPosition:function (t, p){
var n = p == 'end' ? t.value.length : p;
if(document.selection){
var range = t.createTextRange();
range.moveEnd('character', -t.value.length);
range.moveEnd('character', n);
range.moveStart('character', n);
range .select();
}else{
t.setSelectionRange(n,n);
t.focus();
}
},
add:function (t, txt){
var val = t.value;
var wrap = wrap || '' ;
if(document.selection){
document.selection.createRange().text = txt;
} else {
var cp = t.selectionStart;
var ubbLength = t.value.length;
t.value = t.value.slice(0,t.selectionStart) txt t. value.slice(t.selectionStart, ubbLength);
this.setCursorPosition(t, cp txt.length);
};
},
del:function(t, n){
var p = this.getCursorPosition(t);
var s = t.scrollTop;
t.value = t.value.slice(0,p - n) t.value.slice(p);
this.setCursorPosition(t ,p - n);
D.FF && setTimeout(function(){t.scrollTop = s},10);
}
}

Main JS

Copy code The code is as follows:

var AutoTips = function(A){
var elem = A.id ? D.$(A.id) : A.elem;
var checkLength = 5;
var _this = {};
var key = '';
_this.start = function(){
if(!D.$(config.boxID)){
var h = html.slice();
var info = TT.info(elem);
var div = D.DC('DIV');
var bs = D.BS();
h = h.replace('$top$',(info.top bs.top)).
replace('$left$',(info.left bs.left)).
replace('$width$',info.width).
replace('$height$',info.height).
replace('$SCTOP$','0');
div.innerHTML = h;
document.body.appendChild(div);
}else{
_this.updatePosstion();
}
}
_this.keyupFn = function(e){
var e = e || window.event;
var code = e.keyCode;
if(code == 38 || code == 40 || code == 13) {
if(code==13 && D.$(config.wrap).style.display != 'none'){
_this.enter();
}
return false;
}
var cp = TT.getCursorPosition(elem);
if(!cp) return _this.hide();
var valuep = elem.value.slice(0, cp);
var val = valuep.slice(-checkLength);
var chars = val.match(/(w )?@(w )$|@$/);
if(chars == null) return _this.hide();
var char = chars[2] ? chars[2] : '';
D.$(config.valuepWrap).innerHTML = valuep.slice(0,valuep.length - char.length).replace(/n/g,'
').
replace(/s/g,' ') config.positionHTML;
_this.showList(char);
}
_this.showList = function(char){
key = char;
var data = DS.inquiry(friendsData, char, 5);
var html = listHTML.slice();
var h = '';
var len = data.length;
if(len == 0){_this.hide();return;}
var reg = new RegExp(char);
var em = '' char '';
for(var i=0; ivar hm = data[i]['user'].replace(reg,em);
h = html.replace(/$ACCOUNT$|$NAME$/g,data[i]['name']).
replace('$SACCOUNT$',hm).replace('$ID$',data[i]['user']);
}
_this.updatePosstion();
var p = D.$(config.position).getBoundingClientRect();
var bs = D.BS();
var d = D.$(config.wrap).style;
d.top = p.top 20 bs.top 'px';
d.left = p.left - 5 'px';
D.$(config.listWrap).innerHTML = h;
_this.show();
}

_this.KeyDown = function(e){
var e = e || window.event;
var code = e.keyCode;
if(code == 38 || code == 40 || code == 13){
return selectList.selectIndex(code);
}
return true;
}
_this.updatePosstion = function(){
var p = TT.info(elem);
var bs = D.BS();
var d = D.$(config.boxID).style;
d.top = p.top bs.top 'px';
d.left = p.left bs.left 'px';
d.width = p.width 'px';
d.height = p.height 'px';
D.$(config.boxID).scrollTop = elem.scrollTop;
}
_this.show = function(){
selectList.list = D.$(config.listWrap).getElementsByTagName('li');
selectList.index = -1;
selectList._this = _this;
_this.cursorSelect(selectList.list);
elem.onkeydown = _this.KeyDown;
D.$(config.wrap).style.display = 'block';
}
_this.cursorSelect = function(list){
for(var i=0; ilist[i].onmouseover = (function(i){
return function(){selectList.setSelected(i)};
})(i);
list[i].onclick = _this.enter;
}
}
_this.hide = function(){
selectList.list = null;
selectList.index = -1;
selectList._this = null;
D.ER(elem, 'keydown', _this.KeyDown);
D.$(config.wrap).style.display = 'none';
}
_this.bind = function(){
elem.onkeyup = _this.keyupFn;
elem.onclick = _this.keyupFn;
elem.onblur = function(){setTimeout(_this.hide, 100)}
//elem.onkeyup= fn;
//D.EA(elem, 'keyup', _this.keyupFn, false)
//D.EA(elem, 'keyup', fn, false)
//D.EA(elem, 'click', _this.keyupFn, false);
//D.EA(elem, 'blur', function(){setTimeout(_this.hide, 100)}, false);
}
_this.enter = function(){
TT.del(elem, key.length, key);
TT.add(elem, selectList.list[selectList.index].getElementsByTagName('A')[0].rel ' ');
_this.hide();
return false;
}
return _this;
}

作者：idche