I want to detect the barcodein real-time , I the USB barcode scanner to scan barcode to get a price or ISBN , I will detect the text field 's string length . It will trigger some functions if match the condition
我想实时检测条码，我用USB条码扫描器扫描条码得到价格或ISBN，我会检测文本字段的字符串长度。如果符合条件，它将触发一些功能
But I ran the following code and run on Firexfox for a while then my CPU uasge is more than 100% (Intel i5 3570K 3.xGHZ) and also consume much memory,
但我运行以下代码并在Firexfox上运行一段时间，然后我的CPU uasge超过100％（Intel i5 3570K 3.xGHZ）并且还消耗了大量内存，
Is there any better solution can let me achieve the task?
有没有更好的解决方案可以让我实现这个任务？
Thank you all.
谢谢你们。
<head>
<style type="text/css">
.close_ime{ime-mode:disabled;}
</style>
<script src="http://codeorigin.jquery.com/jquery-1.10.2.js" ></script>
<script>
$(document).ready(function () {
var pressed = false;
var chars = [];
$(window).keypress(function (e) {
if (e.which >= 48 && e.which <= 57) {
chars.push(String.fromCharCode(e.which));
}
console.log(e.which + ":" + chars.join("|"));
if (pressed == false) {
setTimeout(function () {
if (chars.length >= 10) {
var barcode = chars.join("");
console.log("Barcode Scanned: " + barcode);
// assign value to some input (or do whatever you want)
$("#barcode").val(barcode);
}
chars = [];
pressed = false;
}, 500);
}
pressed = true;
});
});
$("#barcode").keypress(function (e) {
if (e.which === 13) {
console.log("Prevent form submit.");
e.preventDefault();
}
});
</script>
</head>
<body>
<input type="text" class="close_ime" id="barcode" placeholder="Waiting for barcode scan..." size="40">
</body>
1 个解决方案
#1
4
You can keep a timer variable which captures the setTimeout id. And clear it whenever there is a keypress event.
您可以保留一个捕获setTimeout id的计时器变量。每当有按键事件时清除它。
The only thing I can thing of causing performance problems is setTimeout , as you seem to unnecessarily creating an extra scope for each key press. Also once you clear the timeouts you would not be needing the pressed attribute as well.
我唯一能引起性能问题的是setTimeout，因为你似乎不必要地为每个按键创建一个额外的范围。此外，一旦清除超时，您也不需要按下属性。
$(document).ready(function () {
var chars = [],
timer;
$(window).keypress(function (e) {
// Clear the timer here
clearTimeout(timer);
console.log(e.which + ":" + chars.join("|"));
// You don't need the next statement if the
// keycode does not match in the first place
if (e.which < 48 && e.which > 57) return;
chars.push(String.fromCharCode(e.which));
// checking the length here
// if length less than 10 do nothing
if (chars.length < 10) return;
// Assign the id to the timer
// which will be cleared on next key press
timer = setTimeout(function () {
var barcode = chars.join("");
console.log("Barcode Scanned: " + barcode);
// assign value to some input (or do whatever you want)
$("#barcode").val(barcode);
chars = [];
}, 500);
});
});
$("#barcode").keypress(function (e) {
if (e.which === 13) {
console.log("Prevent form submit.");
e.preventDefault();
}
});
#1
4
You can keep a timer variable which captures the setTimeout id. And clear it whenever there is a keypress event.
您可以保留一个捕获setTimeout id的计时器变量。每当有按键事件时清除它。
The only thing I can thing of causing performance problems is setTimeout , as you seem to unnecessarily creating an extra scope for each key press. Also once you clear the timeouts you would not be needing the pressed attribute as well.
我唯一能引起性能问题的是setTimeout，因为你似乎不必要地为每个按键创建一个额外的范围。此外，一旦清除超时，您也不需要按下属性。
$(document).ready(function () {
var chars = [],
timer;
$(window).keypress(function (e) {
// Clear the timer here
clearTimeout(timer);
console.log(e.which + ":" + chars.join("|"));
// You don't need the next statement if the
// keycode does not match in the first place
if (e.which < 48 && e.which > 57) return;
chars.push(String.fromCharCode(e.which));
// checking the length here
// if length less than 10 do nothing
if (chars.length < 10) return;
// Assign the id to the timer
// which will be cleared on next key press
timer = setTimeout(function () {
var barcode = chars.join("");
console.log("Barcode Scanned: " + barcode);
// assign value to some input (or do whatever you want)
$("#barcode").val(barcode);
chars = [];
}, 500);
});
});
$("#barcode").keypress(function (e) {
if (e.which === 13) {
console.log("Prevent form submit.");
e.preventDefault();
}
});