Javascript Object vs. String and test() Method

Question

I am working on some javascript in a Node-RED function node right now and am running into an issue with a regex comparison.

var incoming = /^(?=.*?\bhello?\b)(?=.*?\bworld\b).*$/;
//var incoming = msg.payload[0].expression;
var sentence = "say hello to the world";
msg.payload = incoming.test(sentence);
return msg;

That works fine and msg.payload now has the value "true"

When I attempt to fetch the "incoming" variable from elsewhere instead of define it though, it fails.

//var incoming = /^(?=.*?\bhello?\b)(?=.*?\bworld\b).*$/;
var incoming = msg.payload[0].expression;
var sentence = "say hello to the world";
msg.payload = incoming.test(sentence);
return msg;

When setting the variable "incoming" this way it does not work and complains "TypeError: incoming.test is not a function". Fetching the typeof(incoming) returns "String" instead of "Object" like it was previously. msg.payload[0].expression contains the same string of characters as setting it inside of the function, it just has a different datatype. What is the best way to handle this?

Thanks!

possible dup https://stackoverflow.com/questions/874709/converting-user-input-string-to-regular-expression — Garr Godfrey, Aug 07 '17 at 02:07
Garr - You are correct, I added RegExp() around the incoming message and it is converting correctly now. Thank you! — Eric, Aug 07 '17 at 02:16

score 1 · Answer 1 · answered Aug 07 '17 at 02:17

1

//var incoming = /^(?=.*?\bhello?\b)(?=.*?\bworld\b).*$/;
var incoming = RegExp(msg.payload[0].expression);
var sentence = "say hello to the world";
msg.payload = incoming.test(sentence);
return msg;

Works as expected, thank you to Garr!

answered Aug 07 '17 at 02:17

Eric

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Javascript Object vs. String and test() Method

1 Answers1