JS 如何獲取掃碼槍輸入數據

1、掃碼槍相當于鍵盤輸入設備，輸入一連串數字后加一個enter鍵。但在實際開發中需要區分是掃描槍輸入還是鍵盤用戶輸入，區別在于掃碼槍輸入很快。

 let code = '';    let lastTime, nextTime;    let lastCode, nextCode;    window.document.onkeypress = (e) => {     if (window.event) { // IE      nextCode = e.keyCode;     } else if (e.which) { // Netscape/Firefox/Opera      nextCode = e.which;     }     if (nextCode === 13) {      if (code.length < 3) return; // 手動輸入的時間不會讓code的長度大于2，所以這里只會對掃碼槍有       console.log(code); // 獲取到掃碼槍輸入的內容，做別的操作       code = '';      lastCode = '';      lastTime = '';      return;     }     nextTime = new Date().getTime();     if (!lastTime && !lastCode) {      code += e.key;     }      if (lastCode && lastTime && nextTime - lastTime > 30) { // 當掃碼前有keypress事件時,防止首字缺失      code = e.key;     } else if (lastCode && lastTime) {      code += e.key;     }     lastCode = nextCode;     lastTime = nextTime;    }

PS：下面看下js獲取USB掃碼槍數據的代碼

前言

找了很多相關的教程不太好用，汲取各家之長總結精簡了一下

原理

1. 掃碼槍掃描到的條形碼每一位會觸發一次onkeydown事件
2. 比如掃描條碼位‘1234567890'的條形碼，會連續執行10次onkeydown事件
3. 條碼掃描到最后一位，會直接觸發Enter

需要引入jQuery，我這里用的是vue

window.onload = (e)=> {   document.onkeydown = (e)=> {   	let nextCode,nextTime = '';   	let lastTime = this.lastTime;   	let code = this.code;     if (window.event) {// IE       nextCode = e.keyCode     } else if (e.which) {// Netscape/Firefox/Opera       nextCode = e.which     }     nextTime = new Date().getTime();     //字母上方 數字鍵0-9 對應鍵碼值 48-57; 數字鍵盤 數字鍵0-9 對應鍵碼值 96-105     if((nextCode>=48&&nextCode<=57) || (nextCode>=96&&nextCode<=105)){     	let codes = {'48':48,'49':49,'50':50,'51':51,'52':52,'53':53,'54':54,'55':55,'56':56,'57':57, 			 '96':48,'97':49,'98':50,'99':51,'100':52,'101':53,'102':54,'103':55,'104':56,'105':57 			}; 			nextCode = codes[nextCode]; 			nextTime = new Date().getTime();     }     // 第二次輸入延遲兩秒，刪除之前的數據重新計算     if(nextTime && lastTime && nextTime-lastTime>2000){ 			code = String.fromCharCode(nextCode);     }else{     	code += String.fromCharCode(nextCode)     }     // 保存數據     this.nextCode = nextCode;     this.lastTime = nextTime;     this.code = code;   	// 鍵入Enter     if(e.which == 13) {       // 判斷 code 長度（這里就獲取到條碼值了，以下業務自由發揮）       	code = $.trim(code)       if (code.length == 13) {         this.$message('A類條碼:' + code);       } else if (code.length == 23) { 				this.$message('B類條碼:' + code);       } else if (code.length == 0) { 				this.$message('請輸入條碼');       } else{       	this.$message('條碼不合法：' + code);       }       //鍵入回車務必清空code值     	this.code = ''     	return false;     }   } }

總結

到此這篇關于js 獲取掃碼槍輸入數據的文章就介紹到這了,