让html5 number 字段显示的 placeholder 可以为非数字

html5_number_field_fixes.js

// jQuery version
$("input[type='number']").each(function(i, el) {
    el.type = "text";
    el.onfocus = function(){this.type="number";};
    el.onblur = function(){this.type="text";};
});

// Stand-alone version
(function(){ var elms = document.querySelectorAll("input"), i=elms.length;
    while(i--) {
        var el=elms[i]; if(el.type=="number"])
            el.type="text",
            el.onfocus = function(){this.type="number";},
            el.onblur = function(){this.type="text";};
    }
})();