jquery – 通过从textarea读取属性的Tinymce html5占位符

我结合了这个答案的代码：
jQuery hasAttr checking to see if there is an attribute on an element获取下面修改的代码处理该场景：

setup: function(ed) {

// Set placeholder
var tinymce_placeholder = $('#'+ed.id);
var attr = tinymce_placeholder.attr('placeholder');

// For some browsers,`attr` is undefined; for others,// `attr` is false.  Check for both.
    if (typeof attr !== 'undefined' && attr !== false) {
        var is_default = false;

        ed.onInit.add(function(ed) {
            // get the current content
            var cont = ed.getContent();

            // If its empty and we have a placeholder set the value
            if(cont.length == 0){
                ed.setContent(tinymce_placeholder.attr("placeholder"));

                // Get updated content
                cont = tinymce_placeholder.attr("placeholder");
            }

            // convert to plain text and compare strings
            is_default = (cont == tinymce_placeholder.attr("placeholder"));

            // nothing to do
            if (!is_default){
                return;
            }
        });

        ed.onMouseDown.add(function(ed,e) {
            // replace the default content on focus if the same as original placeholder
            if (is_default){
                ed.setContent('');
            }
        });
    }
}