Invalid left-hand side in assignment

Hello,

I have this error when I try to add a character to a string. “Error in executeScript_Sandbox code: Invalid left-hand side in assignment”

Here the code : (the variable ${mois is defined before, I don’t write here because it is ok)

{
“Command”: “executeScript_Sandbox”,
“Target”: “{mois} = '0' + {mois};”,
“Value”: “”
}

What am I doing wrong ?

Thank you in advanced

Your command is wrong must edit like this

If you need to sum number you must add number in command

{
“Name”: “merge”,
“CreationDate”: “2020-11-27”,
“Commands”: [
{
“Command”: “store”,
“Target”: “home”,
“Value”: “mois”
},
{
“Command”: “executeScript_Sandbox”,
“Target”: “return (0 + ${mois})”,
“Value”: “mois”
}
]
}

Thanks, but it is not the aim of my code. The aim is to to transform a number to a text, because I have to add a “zero” before the number if this number is inferior to 10.
Example : if the number is “7”, I have to transform this number to string and then add a zero like this : “07”. I just wanna concatenate “0” and the number, not add them.

07 is not number, is text.

Add if command to add 0 in field