shepherdwind · June 6, 2014 11:54 · Jun 6, 2014
diff --git a/idcard.js b/idcard.js
@@ -0,0 +1,43 @@
+/**
+ * 15位身份证转换为18位
+ *
+ */
+function getIdCardNumber18(idCardNumber){
+  if (!idCardNumber) {
+    return null;
+  }
+  // 转换为字符串
+  idCardNumber = '' + idCardNumber;
+
+  if (idCardNumber.length === 18) {
+    return idCardNumber;
+  } else if (idCardNumber.length !== 15) {
+    return null;
+  }
+
+  /* 首先将身份证号码扩展至17位: 将出生年扩展为19XX的形式 */
+  var idCardNumber17 = idCardNumber.substring(0, 6) + "19" + idCardNumber.substring(6);
+
+  /* 计算校验码 */
+  var nSum = 0;
+
+  for (var nCount = 0; nCount < 17; nCount++) {
+    nSum += (parseInt(idCardNumber17[nCount], 10) * (Math.pow(2, 17 - nCount) % 11));
+  }
+
+  nSum = nSum % 11;
+
+  if (nSum <= 1) {
+    nSum = 1 - nSum;
+  } else {
+    nSum = 12 - nSum;
+  }
+  /*
+   * BUGFIX:18位身份证最后一位应该是X
+   */
+  if (nSum === 10) {
+    return idCardNumber17 + "X";
+  } else {
+    return idCardNumber17 += nSum;
+  }
+}