jsonToApexInserts() - Makes it easy to take the JSON that comes from the Salesforce Bulk Data Loader and turn it into Apex that can run in the Developer Console.

jsonToApexInserts.js

function jsonToApexInserts(json, objectName='SObject') {
    const list = JSON.parse(json).map(function(row) {
        return `\tnew ${objectName}(\n`
            + Object.keys(row).map(function(key) {
                return `\t\t${key} = `
                    + JSON.stringify(row[key]).replace(
                        /"([^]*)"/,
                        function(_, inner) {
                            // If this is a date string or a datetime string as specified here
                            // https://developer.salesforce.com/docs/atlas.en-us.api_rest.meta/api_rest/intro_valid_date_formats.htm
                            // turn the values into the appropriate Apex type.
                            var m = /^(\d{4})-(\d\d)-(\d\d)([T ]\d\d:\d\d:\d\d(?:.\d{3}(?:Z|[\+\-]\d\d:\d\d)?)?)?$/.exec(inner);
                            if (m) {
                                var d = +new Date(inner);
                                if (d === d) {
                                  if (m[4]) {
                                      return "DateTime.newInstance(Long.valueOf('" + d + "')) /* " + inner + " */";
                                  }
                                  return 'Date.newInstance(' + [+m[1], +m[2], +m[3]].join(',') + ') /* ' + inner + ' */';
                                }
                            }
                            return "'" + inner.replace(/'/g, "\\'").replace(/\\"/g, '"') + "'";
                        }
                    );
            }).join(',\n') + '\n\t)';
    }).join(',\n');
    return [
        `List<${objectName}> tList = new List<${objectName}> {`,
        `${list}`,
        `};`,
        `insert tList;`,
        `System.debug(JSON.serializePretty(tList));`,
        `delete tList;`
    ].join('\n');
}

~io-config.jsonc

{
  // Name of the function that takes the input string and produces the output string.
  "transform": "jsonToApexInserts",
  // Where to find the code that will be eval'd.
  "files": ["jsonToApexInserts.js"],
  // Add options
  "params": [
    {
      "label": "Object Name",
      "name": "objectName",
      "value": "SObject",
      "type": "text"
    }
  ],
  // Input setup
  "input": { "label": "Input (JSON)", "language": "json" },
  // Output setup
  "output": { "label": "Output (Apex)", "language": "apex" },
  // Type of IO App
  "type": "split"
}

Here is the corresponding IO App:
https://yourjs.com/gist-io/2842b2a58f698c277e283388275a8d8e