javascript - 将条形码扫描到特定的文本框中

Question

我正在研究条形码扫描仪。我使用的条形码扫描器是即插即用类型，无论您将光标放在何处，它都会自动扫描代码。但我想要的是，每次我的扫描仪读取代码时，我是否可以将它扫描到网页上的特定文本框

例如，如果我的表格看起来像这样

<input type="text" name="txtItem" id="txtItem" class="m-wrap w-120" tabindex="6">

<input type="text" name="itemId" id="itemId" class="m-wrap w-120" tabindex="6">

<input type="text" name="itemName" id="itemName" class="m-wrap w-120" tabindex="6">

<input type="text" name="itemQty" id="itemQty" class="m-wrap w-120" tabindex="6">

所以每次我扫描代码时，无论我当前的焦点在哪里，它都应该始终出现在 txtitem 文本框中。

有人可以指导我或帮助我在这里找到解决方案吗？？

Answer 1

一些条形码扫描仪就像另一个输入设备一样。除非您使用计时器来监控输入信息的速度，否则表单无法区分键盘输入的信息与扫描仪输入的信息之间的区别。

一些扫描器将值“粘贴”到焦点控件中 - 其他扫描器发送每个单独的击键。

以下 JSFiddle 能够检测在单个控件上单独发送字符时何时发生输入:

http://jsfiddle.net/PhilM/Bf89R/3/

您可以对其进行调整以使其成为整个表单的委托(delegate)，并从输入它的控件中删除输入并将其放入正确的表单中。

fiddle 的测试 html 是这样的:

<form>
    <input id="scanInput" />
    <button id="reset">Reset</button>
</form>
<br/>
<div>
    <h2>Event Information</h2>
    Start: <span id="startTime"></span> 
    <br/>First Key: <span id="firstKey"></span> 
    <br/>Last Ley: <span id="lastKey"></span> 
    <br/>End: <span id="endTime"></span> 
    <br/>Elapsed: <span id="totalTime"></span>
</div>
<div>
    <h2>Results</h2>
    <div id="resultsList"></div>
</div>

示例 fiddle 的 Javascript 是:

/*
    This code will determine when a code has been either entered manually or
    entered using a scanner.
    It assumes that a code has finished being entered when one of the following
    events occurs:
        • The enter key (keycode 13) is input
        • The input has a minumum length of text and loses focus
        • Input stops after being entered very fast (assumed to be a scanner)
*/

var inputStart, inputStop, firstKey, lastKey, timing, userFinishedEntering;
var minChars = 3;

// handle a key value being entered by either keyboard or scanner
$("#scanInput").keypress(function (e) {
    // restart the timer
    if (timing) {
        clearTimeout(timing);
    }

    // handle the key event
    if (e.which == 13) {
        // Enter key was entered

        // don't submit the form
        e.preventDefault();

        // has the user finished entering manually?
        if ($("#scanInput").val().length >= minChars){
            userFinishedEntering = true; // incase the user pressed the enter key
            inputComplete();
        }
    }
    else {
        // some other key value was entered

        // could be the last character
        inputStop = performance.now();
        lastKey = e.which;

        // don't assume it's finished just yet
        userFinishedEntering = false;

        // is this the first character?
        if (!inputStart) {
            firstKey = e.which;
            inputStart = inputStop;

            // watch for a loss of focus
            $("body").on("blur", "#scanInput", inputBlur);
        }

        // start the timer again
        timing = setTimeout(inputTimeoutHandler, 500);
    }
});

// Assume that a loss of focus means the value has finished being entered
function inputBlur(){
    clearTimeout(timing);
    if ($("#scanInput").val().length >= minChars){
        userFinishedEntering = true;
        inputComplete();
    }
};


// reset the page
$("#reset").click(function (e) {
    e.preventDefault();
    resetValues();
});

function resetValues() {
    // clear the variables
    inputStart = null;
    inputStop = null;
    firstKey = null;
    lastKey = null;
    // clear the results
    inputComplete();
}

// Assume that it is from the scanner if it was entered really fast
function isScannerInput() {
    return (((inputStop - inputStart) / $("#scanInput").val().length) < 15);
}

// Determine if the user is just typing slowly
function isUserFinishedEntering(){
    return !isScannerInput() && userFinishedEntering;
}

function inputTimeoutHandler(){
    // stop listening for a timer event
    clearTimeout(timing);
    // if the value is being entered manually and hasn't finished being entered
    if (!isUserFinishedEntering() || $("#scanInput").val().length < 3) {
        // keep waiting for input
        return;
    }
    else{
        reportValues();
    }
}

// here we decide what to do now that we know a value has been completely entered
function inputComplete(){
    // stop listening for the input to lose focus
    $("body").off("blur", "#scanInput", inputBlur);
    // report the results
    reportValues();
}

function reportValues() {
    // update the metrics
    $("#startTime").text(inputStart == null ? "" : inputStart);
    $("#firstKey").text(firstKey == null ? "" : firstKey);
    $("#endTime").text(inputStop == null ? "" : inputStop);
    $("#lastKey").text(lastKey == null ? "" : lastKey);
    $("#totalTime").text(inputStart == null ? "" : (inputStop - inputStart) + " milliseconds");
    if (!inputStart) {
        // clear the results
        $("#resultsList").html("");
        $("#scanInput").focus().select();
    } else {
        // prepend another result item
        var inputMethod = isScannerInput() ? "Scanner" : "Keyboard";
        $("#resultsList").prepend("<div class='resultItem " + inputMethod + "'>" +
            "<span>Value: " + $("#scanInput").val() + "<br/>" +
            "<span>ms/char: " + ((inputStop - inputStart) / $("#scanInput").val().length) + "</span></br>" +
            "<span>InputMethod: <strong>" + inputMethod + "</strong></span></br>" +
            "</span></div></br>");
        $("#scanInput").focus().select();
        inputStart = null;
    }
}

$("#scanInput").focus();

上面的代码不支持复制/粘贴，但在我们的情况下这不太可能发生。