js 表单之拿到所有参数值

function serialize(form) {
            var parts = [],
                field = null,
                i,
                len,
                j,
                optLen,
                option,
                optValue;

            for (i = 0, len = form.elements.length; i < len; i++) {
                field = form.elements[i];

                switch (field.type) {
                    case "select-one":
                    case "select-multiple":
                        if (field.name.length) {
                            for (j = 0, optLen = field.options.length; j < optLen; j++) {

                                option = field.options[j];
                                if (option.selected) {
                                    optValue = "";
                                    if (option.hasAttribute) {
                                        optValue = (option.hasAttribute("value") ?
                                            option.value : option.text);
                                    } else {
                                        optValue = (option.attributes["value"].specified ?
                                            option.value : option.text);
                                    }
                                    parts.push(encodeURIComponent(field.name) + "=" +
                                        encodeURIComponent(optValue));
                                }
                            }
                        }
                        break;

                    case undefined: //字段集
                    case "file": //文件输入
                    case "submit": //提交按钮
                    case "reset": //重置按钮
                    case "button": //自定义按钮
                        break;

                    case "radio": //单选按钮
                    case "checkbox": //复选框
                        if (!field.checked) {
                            break;
                        }
                    /* 执行默认操作 */
                    default:
                        //不包含没有名字的表单字段
                        if (field.name.length) {
                            parts.push(encodeURIComponent(field.name) + "=" +
                                encodeURIComponent(field.value));
                        }
                }
            }
            return parts.join("&");
        }