node-red-nodes/function/random/random.js

module.exports = function(RED) {
    "use strict";
    function RandomNode(n) {
        RED.nodes.createNode(this,n);

        this.low = n.low
        this.high = n.high
        this.inte = n.inte || false;
        this.property = n.property||"payload";
        var node = this;
        var tmp = {};

        this.on("input", function(msg) {

          tmp.low = 1                 // set this as the default low value
          tmp.low_e = ""
          if (node.low) {             // if the the node has a value use it
              tmp.low = node.low
          } else if ('from' in msg) { // else see if a 'from' is in the msg
              if (Number(msg.from)) { // if it is, and is a number, use it
                  tmp.low = Number(msg.from);
              } else {                // otherwise setup NaN error
                  tmp.low = NaN;
                  tmp.low_e = " From: " + msg.from; // setup to show bad incoming msg.from
              }
          } 
              
          tmp.high = 10               // set this as the default high value  
          tmp.high_e = "";
          if (node.high) {            // if the the node has a value use it 
              tmp.high = node.high
          } else if ('to' in msg) {   // else see if a 'to' is in the msg
              if (Number(msg.to)) {   // if it is, and is a number, use it
                  tmp.high = Number(msg.to);
              } else {                // otherwise setup NaN error 
                  tmp.high = NaN
                  tmp.high_e = " To: " + msg.to // setup to show bad incoming msg.to
              }
          } 
                           
          // if tmp.low or high are not numbers, send an error msg with bad values
          if ( (isNaN(tmp.low)) || (isNaN(tmp.high)) ) {
              this.error("Random: one of the input values is not a number. " + tmp.low_e + tmp.high_e);
          } else {
          // at this point we have valid values so now to generate the random number! 

             // flip the values if low > high so random will work
             var value = 0;
             if (tmp.low > tmp.high) {  
                 value = tmp.low
                 tmp.low = tmp.high
                 tmp.high = value
             }

             // if returning an integer, do a math.ceil() on the low value and a 
             // Math.floor()high value before generate the random number. This must be 
             // done to insure the rounding doesn't round up if using something like 4.7
             // which would end up with 5
             if ( (node.inte == "true") || (node.inte === true) ) {
                 tmp.low  = Math.ceil(tmp.low);
                 tmp.high = Math.floor(tmp.high);
                 // use this to round integers
                 value = Math.round(Math.random() * (tmp.high - tmp.low + 1) + tmp.low - 0.5);
             } else {
                 // use this to round floats
                 value = (Math.random() * (tmp.high - tmp.low)) + tmp.low;
             }
            
             RED.util.setMessageProperty(msg,node.property,value);
             node.send(msg);
          }
        });
    }
    RED.nodes.registerType("random",RandomNode);
}