对占位符文本进行动画处理，使其键入多个短语

Question

对占位符文本进行动画处理，使其键入多个短语

Ben*_*lle 1 javascript input placeholder

我正在使用jsfiddle中的这段代码来为搜索栏中的占位符文本设置动画。最终结果是看起来像正在键入。现在，它只键入一个短语，而我想让它键入一个短语，然后替换为另一个，依此类推。任何帮助将不胜感激。

// your custom placeholder goes here!
var ph = "Search Website e.g. \"Dancing Cats\"",
    searchBar = $('#search'),
    // placeholder loop counter
    phCount = 0;

// function to return random number between
// with min/max range
function randDelay(min, max) {
    return Math.floor(Math.random() * (max-min+1)+min);
}

// function to print placeholder text in a 
// 'typing' effect
function printLetter(string, el) {
    // split string into character seperated array
    var arr = string.split(''),
        input = el,
        // store full placeholder
        origString = string,
        // get current placeholder value
        curPlace = $(input).attr("placeholder"),
        // append next letter to current placeholder
        placeholder = curPlace + arr[phCount];

    setTimeout(function(){
        // print placeholder text
        $(input).attr("placeholder", placeholder);
        // increase loop count
        phCount++;
        // run loop until placeholder is fully printed
        if (phCount < arr.length) {
            printLetter(origString, input);
        }
    // use random speed to simulate
    // 'human' typing
    }, randDelay(50, 90));
}  

// function to init animation
function placeholder() {
    $(searchBar).attr("placeholder", "");
    printLetter(ph, searchBar);
}

placeholder();
$('.submit').click(function(e){
    phCount = 0;
    e.preventDefault();
    placeholder();
});

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Answer 1

lan*_*ova 5

看看我基于ES6 Promise的解决方案。希望这可以帮助。

// Add something to given element placeholder
function addToPlaceholder(toAdd, el) {
    el.attr('placeholder', el.attr('placeholder') + toAdd);
    // Delay between symbols "typing" 
    return new Promise(resolve => setTimeout(resolve, 100));
}

// Cleare placeholder attribute in given element
function clearPlaceholder(el) {
    el.attr("placeholder", "");
}

// Print one phrase
function printPhrase(phrase, el) {
    return new Promise(resolve => {
        // Clear placeholder before typing next phrase
        clearPlaceholder(el);
        let letters = phrase.split('');
        // For each letter in phrase
        letters.reduce(
            (promise, letter, index) => promise.then(_ => {
                // Resolve promise when all letters are typed
                if (index === letters.length - 1) {
                    // Delay before start next phrase "typing"
                    setTimeout(resolve, 1000);
                }
                return addToPlaceholder(letter, el);
            }),
            Promise.resolve()
        );
    });
} 

// Print given phrases to element
function printPhrases(phrases, el) {
    // For each phrase
    // wait for phrase to be typed
    // before start typing next
    phrases.reduce(
        (promise, phrase) => promise.then(_ => printPhrase(phrase, el)), 
        Promise.resolve()
    );
}

// Start typing
function run() {
    let phrases = [
        "Search Website e.g. \"Dancing Cats\"",
        "Lorem ipsum dolor sit amet",
        "Consectetur adipiscing elit",
        "JS is so strange :)"
    ];

    printPhrases(phrases, $('#search'));
}

run();

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.searchbar {
    width: 300px;
    padding: 10px;
}

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<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<!DOCTYPE html>
<html>
<head>
    <meta charset="utf-8">
    <meta name="viewport" content="width=device-width">
    <title>Bin</title>
</head>
<body>
    <input type='text' id="search" class="searchbar" />
</body>
</html>

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