Postman Script

global  : pm.globals.set("key", "value"); collection : pm.collectionVariables.set("key", "value"); environment: pm.environment.set("key", "value"); local  : pm.variables.set("key", "value");

global  : pm.globals.unset("key"); collection : pm.collectionVariables.unset("key"); environment: pm.environment.unset("key"); local  : pm.variables.unset("key");

Before Request

var moment = require("moment"),
    init   = function(cli, ide, eon, today, birthDateMin, birthDateMax){
    birthDateMin = eon(today).subtract(18, 'years').add(1, 'days').format("DD/MM/YYYY");
    birthDateMax = eon(today).subtract(66, 'years').format("DD/MM/YYYY");
    ide.variables.set('adult.birth.date.invalid.min', birthDateMin);
    ide.variables.set('adult.birth.date.invalid.max', birthDateMax);
    cli.info(`adult.birth.date.invalid.min: ${birthDateMin}`);
    cli.info(`adult.birth.date.invalid.max: ${birthDateMax}`);
};
init(console, pm, moment, new Date());

After Request

pm.test("Successful Quotation", function () {
    pm.response.to.have.status(200);
    pm.expect(pm.response.json().message).to.eql("Quotation has been created successfully.");
    pm.collectionVariables.set("quotationRefId", pm.response.json().refId);
});

OOP Script

var moment        = require("moment"),
    beforeRequest = function(console, postman, moment, birthDate, debug){
        birthDate = new AdultBirthDate(console, postman, moment);
        birthDate.setUserVars(debug);
    };

const CHRONO_UNIT = { YEARS : 'years', DAYS  : 'days' },
      DATE_FORMAT = { DD_MM_YYY: 'DD/MM/YYYY' },
      USER_VARS   = { BIRTH_DATE: {
        VALID   : {
            MAX: 'adult.birth.date.valid.max',
            MIN: 'adult.birth.date.valid.min'
        },
        INVALID : {
            MAX: 'adult.birth.date.invalid.max',
            MIN: 'adult.birth.date.invalid.min'
        }
    }};

class AdultBirthDate {
    constructor(console, postman, moment){
        this.cli = console;
        this.ide = postman;
        this.eon = moment;
    }
    
    get validMinDate(){
        return this.eon(new Date()).subtract(18, CHRONO_UNIT.YEARS).format(DATE_FORMAT.DD_MM_YYY);
    }
    get validMaxDate(){
        return this.eon(new Date()).subtract(66, CHRONO_UNIT.YEARS).add(1, CHRONO_UNIT.DAYS).format(DATE_FORMAT.DD_MM_YYY);
    }
    get invalidMinDate(){
        return this.eon(new Date()).subtract(18, CHRONO_UNIT.YEARS).add(1, CHRONO_UNIT.DAYS).format(DATE_FORMAT.DD_MM_YYY);
    }
    get invalidMaxDate(){
        return this.eon(new Date()).subtract(66, CHRONO_UNIT.YEARS).format(DATE_FORMAT.DD_MM_YYY);
    }

    setUserVars(debug){
        debug && this.info();
        this.ide.variables.set(USER_VARS.BIRTH_DATE.VALID.MAX,   this.validMaxDate);
        this.ide.variables.set(USER_VARS.BIRTH_DATE.VALID.MIN,   this.validMinDate);
        this.ide.variables.set(USER_VARS.BIRTH_DATE.INVALID.MAX, this.invalidMaxDate);
        this.ide.variables.set(USER_VARS.BIRTH_DATE.INVALID.MIN, this.invalidMinDate);
    }

    info(message){
        message  = `${USER_VARS.BIRTH_DATE.VALID.MAX}  : ${this.validMaxDate}\n`;
        message += `${USER_VARS.BIRTH_DATE.VALID.MIN}  : ${this.validMinDate}\n`;
        message += `${USER_VARS.BIRTH_DATE.INVALID.MAX}: ${this.invalidMaxDate}\n`;
        message += `${USER_VARS.BIRTH_DATE.INVALID.MIN}: ${this.invalidMinDate}`;
        this.cli.info(message);
    }
}

beforeRequest(console, pm, moment);

References

Postman Subtract time using Moment.js Postman formate date using Moment.js Postman Writing pre-request scripts Postman add time using Moment.js Postman Test script examples Postman JavaScript reference Postman Dynamic variables Postman Variable Scopes Postman Writing tests Scripting in Postman

Defining variables with scope in scripts Postman sharing and persisting data Postman dynamic variables