Question

我使用node-red并且我有以下传入的msg.payload：

[ "=00ECY20WA200_RECV_P1SEL", "true", "=00ECY20WA200_RECV_P2SEL", "true", "=00ECY20WA300_RECV_P2SEL", "true", "=00ECY20WA300_RECV_P1SEL", "true", "=00ECY20WA202_RECV_P1SEL", "true", "=00ECY20WA202_RECV_P2SEL", "false", "=00ECY20WA303_RECV_P2SEL", "true", "=00ECY20WA303_RECV_P1SEL", "true", "=00ECY20WA204_RECV_P1SEL", "false", "=00ECY20WA204_RECV_P2SEL", "true", "=00ECY20WA305_RECV_P2SEL", "false", "=00ECY20WA305_RECV_P1SEL", "false", "=00ECY20WA205_RECV_P1SEL", "false", "=00ECY20WA205_RECV_P2SEL", "false", "=00ECY20WA306_RECV_P1SEL", "true", "=00ECY20WA306_RECV_P2SEL", "true", "=00ECY20WA206_RECV_P1SEL", "false", "=00ECY20WA206_RECV_P2SEL", "true", "=00ECY20WA307_RECV_P1SEL", "true", "=00ECY20WA307_RECV_P2SEL", "true", "=00ECY20WA207_RECV_P1SEL", "false", "=00ECY20WA207_RECV_P2SEL", "false", "=00ECY20WA308_RECV_P1SEL", "false", "=00ECY20WA308_RECV_P2SEL", "true", "=00ECY20WA208_RECV_P1SEL", "false" ]

我试图解析所有＆＃34; true＆＃34;并将它们连接在一个数组（recievingAlarms）中，解析后的项目就是位于布尔运算符之前的项目。我尝试用for循环来做这件事，我很确定我已经创建了一个无限循环，我不确定如何纠正它。这就是我所拥有的：

var recievingAlarms = [];

for (i = 1; i < msg.payload.length; i+2)
    if(msg.payload[i] === true) {
    recievingAlarms.concat(msg.payload[i-1]);
    }
msg.payload = recievingAlarms;
return msg;

Answer 1

你的循环现在是无限的，因为你没有增加i，增加i，你需要用i+2替换i += 2，以便重新分配它的值：

var receivingAlarms = [];

for (var i = 1; i < msg.payload.length; i += 2) {
  if(msg.payload[i] === "true") { //replace true with "true"
    receivingAlarms.push(msg.payload[i-1]); //replace concat with push because msg.payload[i - 1] is not an Array
  }
}

msg.payload = receivingAlarms;
return msg;

您还需要将.concat()更改为.push() - .concat()用于合并/合并两个数组，但msg.payload[i-1]的结果不是数组。此外，需要修改true的条件检查以检查字符串"true"，因为有效内容数组中的值是字符串而不是布尔值。

Answer 2

这是您的解决方案

var recievingAlarms = [];

for (i = 1; i < msg.payload.length; i=i+2)
    if(msg.payload[i] == "true") {
        recievingAlarms=recievingAlarms.concat(msg.payload[i-1]);
    }
msg.payload = recievingAlarms;
return msg;

Answer 3

i永远不会增加，因此循环的条件永远不会评估为false（i将始终小于.length）。
"true"和true不属于同一类型（一个是字符串，另一个是布尔值）。请将msg.payLoad[i]与"true"进行比较。
concat汇总了两个数组。使用push向数组添加新项目。

var recievingAlarms = [];

for (i = 1; i < msg.payload.length; i += 2)
    if(msg.payload[i] === "true")
        recievingAlarms.push(msg.payload[i - 1]);

msg.payload = recievingAlarms;

循环遍历数组并进行解析

3 个答案: