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社区首页 >问答首页 >组件每次呈现时调用函数10次

问组件每次呈现时调用函数10次
EN

Stack Overflow用户
提问于 2018-12-14 16:38:00
回答 1查看 150关注 0票数 0

我正在尝试测试我的一个组件。它是一个来自Material的NavigationDrawer，它有一个名为toggleDrawer()的道具，它就是这样做的，并且可以切换抽屉。

每次组件呈现时，它都在1ms - 2ms的范围内调用toggleDrawer()函数10次。我很难理解它为什么要这样做，如果可能的话，我想解决这个问题。

这是构成部分：

代码语言：javascript
复制
import React from "react";
import PropTypes from "prop-types";
import { withStyles } from "@material-ui/core/styles";
import { styles } from "../styles/NavigationDrawerStyles";
import Drawer from "@material-ui/core/Drawer";
import List from "@material-ui/core/List";
import ListItem from "@material-ui/core/ListItem";
import ListItemText from "@material-ui/core/ListItemText";
import ListItemIcon from "@material-ui/core/ListItemIcon";
import Collapse from "@material-ui/core/Collapse";
import ExpandLess from "@material-ui/icons/ExpandLess";
import ExpandMore from "@material-ui/icons/ExpandMore";
import ViewListIcon from "@material-ui/icons/ViewListOutlined";
import CreateOutlinedIcon from "@material-ui/icons/CreateOutlined";
import ShuffleIcon from "@material-ui/icons/Shuffle";
import ChevronLeftIcon from "@material-ui/icons/ChevronLeft";
import HomeIcon from "@material-ui/icons/HomeOutlined";
import ContactsIcon from "@material-ui/icons/ContactsOutlined";
import BusinessIcon from "@material-ui/icons/BusinessOutlined";
import IconButton from "@material-ui/core/IconButton";
import DescriptionIcon from "@material-ui/icons/DescriptionOutlined";
import DashboardOutlinedIcon from "@material-ui/icons/DashboardOutlined";
import BookOutlinedIcon from "@material-ui/icons/BookOutlined";
import Divider from "@material-ui/core/Divider";
import { Link } from "react-router-dom";

class NavigationDrawer extends React.Component {
  constructor(props) {
    super(props);

    this.state = {
      postsOpen: false,
      policiesOpen: false
    };
  }

  handlePostsClick = () => {
    this.setState(state => ({ postsOpen: !state.postsOpen }));
  };

  handlePoliciesClick = () => {
    this.setState(state => ({ policiesOpen: !state.policiesOpen }));
  };

  render() {
    const { classes, toggleDrawer, open } = this.props;
    const { postsOpen, policiesOpen } = this.state;

    return (
      <React.Fragment>
        <Drawer
          open={open}
          onClose={toggleDrawer(false)}
          className={classes.drawerPaper}
        >
          <div
            tabIndex={0}
            role="button"
            //onClick={toggleDrawer(false)}
            //onKeyDown={toggleDrawer(false)}
            className={classes.list}
          >
            <div className={classes.drawerHeader}>
              <IconButton
                className={classes.CloseIcon}
                onClick={toggleDrawer(false)}
              >
                <ChevronLeftIcon />
              </IconButton>
            </div>
            <Divider />
            <List>
              <ListItem
                button
                component={Link}
                to="/"
                onClick={toggleDrawer(false)}
              >
                <ListItemIcon>
                  <HomeIcon />
                </ListItemIcon>
                <ListItemText inset primary="Home" />
              </ListItem>
              <ListItem button onClick={this.handlePostsClick}>
                <ListItemIcon>
                  <DashboardOutlinedIcon />
                </ListItemIcon>
                <ListItemText inset primary="Posts" />
                {postsOpen ? <ExpandLess /> : <ExpandMore />}
              </ListItem>
              <Collapse in={postsOpen} timeout="auto" unmountOnExit>
                <List component="div" disablePadding>
                  <ListItem
                    button
                    className={classes.nested}
                    id="posts-nested-dropdown"
                    component={Link}
                    to="/posts/"
                    onClick={toggleDrawer(false)}
                  >
                    <ListItemIcon>
                      <ViewListIcon />
                    </ListItemIcon>
                    <ListItemText inset primary="Recent Posts" />
                  </ListItem>
                  <ListItem
                    button
                    className={classes.nested}
                    component={Link}
                    to="/posts/create/"
                    onClick={toggleDrawer(false)}
                  >
                    <ListItemIcon>
                      <CreateOutlinedIcon />
                    </ListItemIcon>
                    <ListItemText inset primary="Create a Post" />
                  </ListItem>
                  <ListItem button className={classes.nested}>
                    <ListItemIcon>
                      <ShuffleIcon />
                    </ListItemIcon>
                    <ListItemText inset primary="Random Post" />
                  </ListItem>
                </List>
              </Collapse>
              <ListItem
                button
                component={Link}
                to="/about"
                onClick={toggleDrawer(false)}
              >
                <ListItemIcon>
                  <BusinessIcon />
                </ListItemIcon>
                <ListItemText inset primary="About" />
              </ListItem>
              <ListItem
                button
                component={Link}
                to="/contact"
                onClick={toggleDrawer(false)}
              >
                <ListItemIcon>
                  <ContactsIcon />
                </ListItemIcon>
                <ListItemText inset primary="Contact" />
              </ListItem>
              <ListItem
                button
                component="a"
                href="http://docs.chbresser.com"
                onClick={toggleDrawer(false)}
              >
                <ListItemIcon>
                  <DescriptionIcon />
                </ListItemIcon>
                <ListItemText inset primary="Docs" />
              </ListItem>
              <Divider />
              <ListItem button onClick={this.handlePoliciesClick}>
                <ListItemIcon>
                  <BookOutlinedIcon />
                </ListItemIcon>
                <ListItemText inset primary="Important Policies" />
                {policiesOpen ? <ExpandLess /> : <ExpandMore />}
              </ListItem>
              <Collapse in={policiesOpen} timeout="auto" unmountOnExit>
                <List component="div" disablePadding>
                  <ListItem
                    button
                    className={classes.nested}
                    component={Link}
                    to="/privacy/"
                    onClick={toggleDrawer(false)}
                  >
                    <ListItemIcon>
                      <ViewListIcon />
                    </ListItemIcon>
                    <ListItemText inset primary="Privacy Policy" />
                  </ListItem>
                  <ListItem
                    button
                    className={classes.nested}
                    component={Link}
                    to="/terms/"
                    onClick={toggleDrawer(false)}
                  >
                    <ListItemIcon>
                      <ViewListIcon />
                    </ListItemIcon>
                    <ListItemText inset primary="Terms and Conditions" />
                  </ListItem>
                </List>
              </Collapse>
            </List>

            <div className={classes.drawerFooter}>
              <i
                className={`fas fa-hand-holding-heart ${classes.footerIcon}`}
              />{" "}
              Made with love by the TechHorizon team.
              <br />
            </div>
          </div>
        </Drawer>
      </React.Fragment>
    );
  }
}

NavigationDrawer.propTypes = {
  classes: PropTypes.object.isRequired,
  toggleDrawer: PropTypes.func.isRequired
};

export default withStyles(styles)(NavigationDrawer);

到目前为止这是我的测试：

代码语言：javascript
复制
import { createShallow } from "@material-ui/core/test-utils";
import React from "react";
import NavigationDrawer from "../components/NavigationDrawer";
import "jest-dom/extend-expect";

const toggleDrawer = jest.fn();

describe("<NavigationDrawer />", () => {
  let shallow;

  beforeEach(() => {
    shallow = createShallow({ dive: true });
  });

  it("renders a Drawer", () => {
    const page = shallow(<NavigationDrawer toggleDrawer={toggleDrawer} />);
    expect(toggleDrawer.mock.calls.length).toEqual(0);
    expect(page.find("WithStyles(Drawer)").length).toEqual(1);
  });

  it("renders the main List and 2 dropdown Lists", () => {
    const page = shallow(<NavigationDrawer toggleDrawer={toggleDrawer} />);
    expect(page.find("WithStyles(List)").length).toEqual(3);
  });

  it("opens posts menu on click", () => {
    const page = shallow(<NavigationDrawer toggleDrawer={toggleDrawer} />);
    expect(toggleDrawer.mock.calls.length).toEqual(1);
  });
});

每次调用toggleDrawer()的测试次数都会多10次。

enzyme
javascript
reactjs
EN

回答 1

Stack Overflow用户

回答已采纳

发布于 2018-12-14 16:40:24

这一行是您的问题(重复了10次)：

代码语言：javascript
复制
onClick={toggleDrawer(false)}

它不是将带有此参数的函数传递给ListItem的道具，而是调用toggleDrawer(false)并将该函数调用的结果作为支柱传递。

如果希望在触发toggleDrawer()事件时使用参数false调用onClick，则应将其包装为如下函数：

代码语言：javascript
复制
onClick={() => toggleDrawer(false)}

或者，您可以像这样使用Function.prototype.bind()：

代码语言：javascript
复制
onClick={toggleDrawer.bind(this, false)}

这两个选项都被列为推荐选项在反应文档中。

这种行为是明显不同，因为您将如何在普通的HTML中附加事件处理程序：

HTML: <div onclick="handleEvent()" />

JSX: <div onClick={handleEvent} />

票数 4
EN
页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：

https://stackoverflow.com/questions/53783676

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