Get a value from an object and use that value to fill up other keys in that same object under a cond-CodePudding

So here's an example:

{
    "e": "------5/6-----8\\6-|-------------------|-------------------",
    "B": "-----------9-------|---------6p8---(6)-|-------------------",
    "G": "--8----------------|---8h9-------------|--<8>--------------",
    "D": "",
    "A": "",
    "E": ""
}

I want to get value from this object that is not empty. (So that could be from the e key or from the B key. As long it's not empty.)
Then I'm replacing that value using this expression here:

str.replace(/[0-9-. a-zA-Z // \ ~ ( ) < >]/g, '-');

It's for replacing the numbers, letters, and other characters into dashes.

I want to use that value with the dashes and pipe chars only to fill up the other keys inside the same object that are empty.
In the end, I want it to look something like this:

{
   "e": "------5/6-----8\\6-|-------------------|-------------------",
   "B": "-----------9-------|---------6p8---(6)-|-------------------",
   "G": "--8----------------|---8h9-------------|--<8>--------------",
   "D": "-------------------|-------------------|-------------------",
   "A": "-------------------|-------------------|-------------------",
   "E": "-------------------|-------------------|-------------------"
}

I have no idea how to achieve this in code. Please help.

CodePudding user response：

You should just iterate between your object's keys like this:

// find first non-empty field, !! - conversion to boolean
let nonEmptyKey = Object.keys(obj).find(key => !!obj[key]);

for(let key of Object.keys(obj)) {
  // check if value is empty
  if(!obj[key]) {
    obj[key] = obj[nonEmptyKey].replace(/[0-9-. a-zA-Z // \ ~ ( ) < >]/g, '-');
  }
}

Also, you can simplify your regex to this:

// replace all symbols except - and |
str.replace(/[^-|]/g, '-');

CodePudding user response：

You can loop over each key value pair and replace the value if its empty. Be aware that a backslash is used for escaping a character. To fix this we first replace the backslashes with dashes and then replace the rest.

The regex could also be simplified to /[^-|]/g which means replace all symbols except - and |

const lines = {
    "e": "------5/6-----8\\6-|-------------------|-------------------",
    "B": "-----------9-------|---------6p8---(6)-|-------------------",
    "G": "--8----------------|---8h9-------------|--<8>--------------",
    "D": "",
    "A": "",
    "E": ""
};

const createFullLines = (lines) => {
  // Find a line that is not empty
  const filledLine = Object.values(lines).find((line) => line.trim());
  
  // Exit if all lines are empty
  if(!filledLine) return lines;
  
  // Create new line with only dashes
  const newLine = filledLine.replace('\\', '--').replace(/[^-|]/g, '-');
  
  // Update lines
  for(const key in lines) {
    lines[key] ||= newLine;
  }
  
  return lines;
}

const result = createFullLines(lines);

console.log(result);