Get sub string from variable

Developers
1

I Recieved the string “Voeg 45 g pH- toe”. It’s saved in a variable called “PHMessage”

I want to save the numeric value (45) into a number variable

What is the best way to do this?

2

Inside of an app or in a flow?

3

Good question flow would be nice but a script is okay to because I run that first setting the value and use it afterwards

4

You can use the HomeyScript flow card and pass the token with the string as input parameter.

The script can be like this:

return args[0].split(’ ')[1];

args is a input array.
args[0] is your token value.
The text is splitted ad blanks and the second element is returned.

5

It’s not always on the same position, but always between to words/phrases

6

If it’s the only number then something like this:
Just a simple loop through the split array. You can use forEach, too.

let array = args[0].split(’ ');
for (let i=0; i<array.length; i++){
  if (typeof array[i] == 'number'){
    return parseFloat(array[i]);
}
throw new Error('No number found');

Just written down and not tested :slight_smile:

7

This is what regular expressions are used for:

const str   = args[0];
const match = str.match(/\d+/)[0];
if (match) {
  let num = Number(match[0]);
  ...
}

This will find the first number in the string and doesn’t match negative or decimal numbers.