How to use the graphql.GraphQLScalarType function in graphql

import { GraphQLScalarType, Kind } from 'graphql';

const parseValue = value => value; // value from the client

const serialize = value => {
  // value sent to the client
  value.buffer = value.buffer.toString('base64');
  return value;
};

const parseLiteral = ast => ast.value; // ast is always string format

const ImageScalarType = new GraphQLScalarType({
  name: 'ImageScalar',
  description: 'Image manipulating scalar',
  parseValue,
  serialize,
  parseLiteral
});

export default ImageScalarType;

const { GraphQLScalarType } = require('graphql')
const phone = require('phone')

const TOLL_FREE_PREFIX = ['800', '844', '855', '866', '877', '888']

const parse = (value) => {
  const num = String(value).replace(/\D/g, '').slice(-10)
  if (num.length === 10 && TOLL_FREE_PREFIX.some(v => v === num.substr(0, 3))) {
    return `+1${num}`
  }
  return phone(String(value))[0]
}

// Index 0 is phone, index 1 is country code
module.exports = new GraphQLScalarType({
  name: 'PhoneNumber',
  serialize: parse,
  parseValue: parse,
  parseLiteral (ast) {
    return parse(ast.value)
  }
})

import contentResolvers from './content';
import contentRemoteResolvers from './content_remote';
import { GraphQLScalarType } from 'graphql';
import { Kind } from 'graphql/language';
import userResolvers from './user';
import userRemoteResolvers from './user_remote';

const exampleResolvers = {
  Date: new GraphQLScalarType({
    name: 'Date',
    description: 'Date custom scalar type',
    parseValue(value) {
      return new Date(value); // value from the client
    },
    serialize(value) {
      return value.getTime(); // value sent to the client
    },
    parseLiteral(ast) {
      if (ast.kind === Kind.INT) {
        return parseInt(ast.value, 10); // ast value is always in string format
      }
      return null;
    },
  }),

import { BigNumber } from "bignumber.js";
import { ASTNode, GraphQLScalarType } from "graphql";
import * as language from "graphql/language/kinds";

export const BigNumberScalar = new GraphQLScalarType({
  name: "BigNumber",
  description:
    "The BigNumber scalar type represents numeric values with precision as in https://github.com/MikeMcl/bignumber.js/",
  serialize(value: BigNumber): string {
    return new BigNumber(value).toString();
  },
  parseValue(value: string): string {
    return new BigNumber(value).toString(10);
  },
  // value received from the client
  parseLiteral(ast: ASTNode): string | null {
    switch (ast.kind) {
      case language.Kind.INT:
      case language.Kind.FLOAT:
        return new BigNumber(ast.value).toString(10);
      default:

}

function parseLiteral(
  ast:
    | { kind: typeof Kind.INT; value: number }
    | { kind: typeof Kind.STRING; value: string }
    | any
): null | Date {
  if (ast.kind === Kind.INT || ast.kind === Kind.STRING) {
    return parseValue(ast.value);
  }

  return null;
}

export const GraphQLTimestamp = new GraphQLScalarType({
  name: "Timestamp",
  description:
    "The javascript `Date` as integer. Type represents date and time as number of milliseconds from start of UNIX epoch.",
  serialize,
  parseValue,
  parseLiteral
});

const parseObjectFields = fields => {
  if (Array.isArray(fields)) {
    return fields.reduce(
      (object, field) => ({
        ...object,
        [field.name.value]: parseValue(field.value),
      }),
      {}
    );
  }

  throw new TypeValidationError(fields, 'Object');
};

const ANY = new GraphQLScalarType({
  name: 'Any',
  description:
    'The Any scalar type is used in operations and types that involve any type of value.',
  parseValue: value => value,
  serialize: value => value,
  parseLiteral: ast => parseValue(ast),
});

const OBJECT = new GraphQLScalarType({
  name: 'Object',
  description:
    'The Object scalar type is used in operations and types that involve objects.',
  parseValue(value) {
    if (typeof value === 'object') {
      return value;
    }

throw new TSError(`${keyName}: ${keyValue} is not a valid string`);
            }
        }

        if (keyName === 'array') {
            if (keyValue != null && typeof keyValue !== 'boolean') {
                throw new TSError(`${keyName}: ${keyValue} is not a valid boolean`);
            }
        }

        accum[fieldName] = { [keyName]: keyValue };
        return accum;
    }, {});
}

export const GraphQLDataType = new GraphQLScalarType({
    name: 'GraphQLDataType',
    description: 'Scalar type for data type configs',
    serialize,
    parseValue,
    parseLiteral,
});

export function formatSchema(schemaStr: string) {
    const schema = buildSchema(schemaStr, { commentDescriptions: true });
    return printSchema(schema, {
        commentDescriptions: true
    });
}

parseLiteral: function parseLiteral(ast) {
    switch (ast.kind) {
      case _language.Kind.INT:
        return ast.value;
      case _language.Kind.LIST:
        return ast.values.map(timeRange.parseLiteral);
      default:
        return null;
    }
  }
};

exports.default = {
  schema: '\n    scalar TimeRange\n  ',
  resolvers: {
    TimeRange: new _graphql.GraphQLScalarType(timeRange)
  }
};
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});

          return value;
        }
      case _language.Kind.LIST:
        return ast.values.map(json.parseLiteral);
      default:
        return null;
    }
  }
};

exports.default = {
  schema: '\n    scalar Json\n  ',
  resolvers: {
    Json: new _graphql.GraphQLScalarType(json)
  }
};
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deprecationReason: value.deprecationReason,
        description: value.description,
        astNode: value.astNode,
      };
    });
    return new GraphQLEnumType({
      name: type.name,
      description: type.description,
      astNode: type.astNode,
      values: newValues,
    });
  } else if (type instanceof GraphQLScalarType) {
    if (keepResolvers || isSpecifiedScalarType(type)) {
      return type;
    } else {
      return new GraphQLScalarType({
        name: type.name,
        description: type.description,
        astNode: type.astNode,
        serialize(value: any) {
          return value;
        },
        parseValue(value: any) {
          return value;
        },
        parseLiteral(ast: ValueNode) {
          return parseLiteral(ast);
        },
      });
    }
  } else {
    throw new Error(`Invalid type ${type}`);