前端实现打印 样式不丢失

const Print = function (dom, options) {
    if (!(this instanceof Print)) return new Print(dom, options);

    this.options = this.extend({
        noPrint: '.no-print',
        onStart: function () {},
        onEnd: function () {}
    }, options);

    if ((typeof dom) === "string") {
        this.dom = document.querySelector(dom);
    } else {
        this.dom = dom;
    }

    this.init();
};
Print.prototype = {
    init: function () {
        let content = this.getStyle() + this.getHtml();
        this.writeIframe(content);
    },
    extend: function (obj, obj2) {
        for (let k in obj2) {
            obj[k] = obj2[k];
        }
        return obj;
    },

    getStyle: function () {
        let str = "";
        let styles = document.querySelectorAll('style,link');
        for (let i = 0; i < styles.length; i++) {
            str += styles[i].outerHTML;
        }
        str += "<style>" + (this.options.noPrint ? this.options.noPrint : '.no-print') + "{display:none;}</style>";

        return str;
    },

    getHtml: function () {
        let inputs = document.querySelectorAll('input');
        let textareas = document.querySelectorAll('textarea');
        let selects = document.querySelectorAll('select');

        for (let k in inputs) {
            if (inputs[k].type === "checkbox" || inputs[k].type === "radio") {
                if (inputs[k].checked === true) {
                    inputs[k].setAttribute('checked', "checked");
                } else {
                    inputs[k].removeAttribute('checked');
                }
            } else if (inputs[k].type === "text") {
                inputs[k].setAttribute('value', inputs[k].value);
            }
        }

        for (let k2 in textareas) {
            if (textareas[k2].type === 'textarea') {
                textareas[k2].innerHTML = textareas[k2].value;
            }
        }

        for (let k3 in selects) {
            if (selects[k3].type === 'select-one') {
                let child = selects[k3].children;
                for (let i in child) {
                    if (child[i].tagName === 'OPTION') {
                        if (child[i].selected === true) {
                            child[i].setAttribute('selected', "selected");
                        } else {
                            child[i].removeAttribute('selected');
                        }
                    }
                }
            }
        }
        return this.dom.outerHTML;
    },

    writeIframe: function (content) {
        let w;
        let doc;
        let iframe = document.createElement('iframe');
        let f = document.body.appendChild(iframe);
        iframe.id = "myIframe";
        iframe.style = "position:absolute;width:0;height:0;top:-10px;left:-10px;";
        w = f.contentWindow || f.contentDocument;
        doc = f.contentDocument || f.contentWindow.document;
        doc.open();
        doc.write(content);
        doc.close();
        this.toPrint(w, function () {
            document.body.removeChild(iframe);
        });
    },

    toPrint: function (w, cb) {
        let _this = this;
        w.onload = function () {
            try {
                setTimeout(function () {
                    w.focus();
                    typeof _this.options.onStart === 'function' && _this.options.onStart();
                    if (!w.document.execCommand('print', false, null)) {
                        w.print();
                    }
                    typeof _this.options.onEnd === 'function' && _this.options.onEnd();
                    w.close();
                    cb && cb();
                });
            } catch (err) {
                console.log('err', err);
            }
        };
    }
};

组件里引用js 直接调用