trigger pipeline job from jenkins pipeline script

Question

I have two pipeline jobs which are job A and job B. I need to trigger job B while job A is running.. because job A will not finish due to some API calls. so I need to start the next pipeline job B.

how can we trigger another pipeline job from the Jenkins file?
All the parallel blocks of a,b,c need to run.

Below I have pasted the job A Jenkins script.

    pipeline {
    agent any
    stages {
        stage('need to run parallelly'){
             steps {
                  parallel(
            a:{
                dir('file path'){
                bat """
                npm install
                """
                }
            },
            b:{
              dir('file path'){
                    bat """
                    npm start
                    """
                  }  
            },
            c:{
              build job: 'JOB_B'
            }
            )
        }
        }           
    }
    }

Answer 1

You have an example here.
In your case, try:

pipeline {
agent any   
stages {
    stage('need to run parallelly'){
        steps{
            script{
                parallel(
                    a:{
                        dir('file path'){
                            bat """
                            npm install
                            """
                        }
                    },
                    b:{
                        dir('file path'){
                            bat """
                            npm start
                            """
                        }  
                    },
                    "build":{
                        build job: 'JenkinsTest'
                    },
                )
            }
        }
    }
}