This is the structure of my data

const resourecesSalary = [[
  {
    designationName: 'backend developer',
    departmentName: 'web development',
    salary: {
      monthly: 10000   
    }
  },
  {
    designationName: 'frontend developer',
    departmentName: 'web development',
    salary: {
      monthly: 10000
    }
  },
  {
    designationName: 'sr seo strategist',
    departmentName: 'seo',
    salary: {
      monthly: 10000
    }
  },
  {
    designationName: 'seo strategist',
    departmentName: 'seo',
    salary: {
      monthly: 5000
    }
  },
   {
    designationName: 'account manager',
    departmentName: 'client servicing',
    salary: {
      monthly: 15000
    }
  }
]

The idea that am trying to implement is that I need to generate total department wise cost from the above data. Example

const departmentWiseCost =[{
departmentName:'web development',
totalCost:20000               //added the salary of resources from web development department
},
{
departmentName:'seo'
totalCost:15000              //added the salary of resources from seo department
},
{
departmentName:'client servicing'
totalCost:15000             //added the salary of resources from client servicing department
}]

Please help me to resolve this as am a beginner in coding.