How to extract raw value from JSON and cut it into pieces by size

Sample data:

{
  "var_name1": {},
  "var_name2": "string",
  "var_name3": "long string",
  "var_name4": 15
}

Fill Bash variable with extracted long string raw value from JSON:

VAR_NAME=`cat file.json | jq --raw-output '.var_name3'`

Then reference "chunks" of data using Bash variable index modifiers, e.g. by 255 characters:

• ${VAR_NAME:0:255}
• ${VAR_NAME:255:255}
• ${VAR_NAME:510:255}
• ${VAR_NAME:765:255}
• ${VAR_NAME:1020:255}

One-liner alternative extracting and displaying output in single command line:

VAR_NAME=`cat file.json  | jq --raw-output '.var_name3'` ; echo $VAR_NAME ; echo ${VAR_NAME:0:255} ; echo ${VAR_NAME:255:255} ; echo ${VAR_NAME:510:255} ; echo ${VAR_NAME:765:255} ; echo ${VAR_NAME:1020:255}