«
»

如何得知HTML Page裡目前Focus的Element?

document.activeElement 這個變數會指向目前取得focus的element

所以，我們可以利用這個變數來判斷某一個element (如:input)是否有focus
依據有無focus，然後做不同的處理方式

Example:

if( document.activeElement == element ) {
    if( text == "" || text == defaultText ) {
        inp.removeClass("ghost");
        inp.val("");
    }
} else {
    if( text == "" || text == defaultText ) {
        inp.addClass("ghost");
        inp.val(defaultText);
    } else {
        inp.removeClass("ghost");
    }
}

這段code是用來做下面ghost(輸入欄位預設文字)這個效果:

滑鼠點了Twitter的輸入欄位後:

Reference:
http://stackoverflow.com/questions/497094/how-do-i-find-out-which-javascript-element-has-focus

Tags: , ,

This entry was posted on Friday, March 5th, 2010 at 11:47 pm and is filed under 技術筆記. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.

Leave a Reply