css 防抖动

Posted 2021-05-13

Debouncing
----------
This example demonstrates how to add a 1sec debounce, so that suggestions are retrieved only after user stopped typing for 1sec.

A [Pen](https://codepen.io/motekim/pen/gZgKMa) by [mike lange](https://codepen.io/motekim) on [CodePen](https://codepen.io).

[License](https://codepen.io/motekim/pen/gZgKMa/license).

<h2>Debouncing</h2>
<div id="app"></div>

/* ---------- */
/*    Data    */
/* ---------- */

const languages = [
  {
    name: 'C',
    year: 1972
  },
  {
    name: 'C#',
    year: 2000
  },
  {
    name: 'C++',
    year: 1983
  },
  {
    name: 'Clojure',
    year: 2007
  },
  {
    name: 'Elm',
    year: 2012
  },
  {
    name: 'Go',
    year: 2009
  },
  {
    name: 'Haskell',
    year: 1990
  },
  {
    name: 'Java',
    year: 1995
  },
  {
    name: 'Javascript',
    year: 1995
  },
  {
    name: 'Perl',
    year: 1987
  },
  {
    name: 'PHP',
    year: 1995
  },
  {
    name: 'Python',
    year: 1991
  },
  {
    name: 'Ruby',
    year: 1995
  },
  {
    name: 'Scala',
    year: 2003
  }
];

function getMatchingLanguages(value) {
  const escapedValue = escapeRegexCharacters(value.trim());
  
  if (escapedValue === '') {
    return [];
  }
  
  const regex = new RegExp('^' + escapedValue, 'i');

  return languages.filter(language => regex.test(language.name));
}

/* ----------- */
/*    Utils    */
/* ----------- */

// https://developer.mozilla.org/en/docs/Web/JavaScript/Guide/Regular_Expressions#Using_Special_Characters
function escapeRegexCharacters(str) {
  return str.replace(/[.*+?^${}()|[\]\\]/g, '\\$&');
}

function randomDelay() {
  return 300 + Math.random() * 1000;
}

/* --------------- */
/*    Component    */
/* --------------- */

function getSuggestionValue(suggestion) {
  return suggestion.name;
}

function renderSuggestion(suggestion) {
  return (
    <span>{suggestion.name}</span>
  );
}

class App extends React.Component {
  constructor() {
    super();

    this.state = {
      value: '',
      suggestions: [],
      isLoading: false
    };

    this.debouncedLoadSuggestions = _.debounce(this.loadSuggestions, 1000); // 1000ms is chosen for demo purposes only.
  }
  
  loadSuggestions(value) {
    this.setState({
      isLoading: true
    });
    
    // Fake an AJAX call
    setTimeout(() => {
      const suggestions = getMatchingLanguages(value);

      if (value === this.state.value) {
        this.setState({
          isLoading: false,
          suggestions
        });
      } else { // Ignore suggestions if input value changed
        this.setState({
          isLoading: false
        });
      }
    }, randomDelay());
  }
  
  onChange = (event, { newValue }) => {
    this.setState({
      value: newValue
    });
  };
  
  onSuggestionsFetchRequested = ({ value }) => {
    this.debouncedLoadSuggestions(value);
  };

  onSuggestionsClearRequested = () => {
    this.setState({
      suggestions: []
    });
  };

  render() {
    const { value, suggestions, isLoading } = this.state;
    const inputProps = {
      placeholder: "Type 'c'",
      value,
      onChange: this.onChange
    };
    const status = (isLoading ? 'Loading...' : 'Type to load suggestions');

    return (
      <div>
        <div className="status">
          <strong>Status:</strong> {status}
        </div>
        <Autosuggest 
          suggestions={suggestions}
          onSuggestionsFetchRequested={this.onSuggestionsFetchRequested}
          onSuggestionsClearRequested={this.onSuggestionsClearRequested}
          getSuggestionValue={getSuggestionValue}
          renderSuggestion={renderSuggestion}
          inputProps={inputProps} />
      </div>
    );
  }
}

ReactDOM.render(<App />, document.getElementById('app'));

<script src="https://unpkg.com/react@15.4.2/dist/react.js"></script>
<script src="https://unpkg.com/react-dom@15.4.2/dist/react-dom.js"></script>
<script src="https://unpkg.com/react-autosuggest@9.0.0/dist/standalone/autosuggest.js"></script>
<script src="https://unpkg.com/lodash@4.17.4/lodash.js"></script>

body {
  font-family: Helvetica, sans-serif;
}

.status {
  line-height: 52px;
}

.react-autosuggest__container {
  position: relative;
}

.react-autosuggest__input {
  width: 240px;
  height: 30px;
  padding: 10px 20px;
  font-family: Helvetica, sans-serif;
  font-weight: 300;
  font-size: 16px;
  border: 1px solid #aaa;
  border-radius: 4px;
}

.react-autosuggest__input--focused {
  outline: none;
}

.react-autosuggest__input--open {
  border-bottom-left-radius: 0;
  border-bottom-right-radius: 0;
}

.react-autosuggest__suggestions-container {
  display: none;
}

.react-autosuggest__suggestions-container--open {
  display: block;
  position: absolute;
  top: 51px;
  width: 280px;
  border: 1px solid #aaa;
  background-color: #fff;
  font-family: Helvetica, sans-serif;
  font-weight: 300;
  font-size: 16px;
  border-bottom-left-radius: 4px;
  border-bottom-right-radius: 4px;
  z-index: 2;
}

.react-autosuggest__suggestions-list {
  margin: 0;
  padding: 0;
  list-style-type: none;
}

.react-autosuggest__suggestion {
  cursor: pointer;
  padding: 10px 20px;
}

.react-autosuggest__suggestion--highlighted {
  background-color: #ddd;
}