Get expected goals from probabilities

expg_from_probabilities.r

# library(implied)
# 
# dta <- read.csv('E0.csv')
# 
# # Convert bookmaker odds to probabilities.
# imp <- implied_probabilities(dta[,c('B365H', 'B365D', 'B365A')], method='power')
# prob_mat <- imp$probabilities
# 
# # Convert probabilities to expected goals.
# expg_res <- expg_from_probabilities(prob_mat)


lambda_sq_error <- function(lambda_pars, trgt_probs, maxgoals=25){
  
  lambda_pars <- exp(lambda_pars) # trick to avoid negaive lambda parameters.
  hda_probs <- numeric(3)
  probmat <- dpois(0:maxgoals, lambda=lambda_pars[1]) %o% dpois(0:maxgoals, lambda=lambda_pars[2])
  
  hda_probs[2] <- sum(diag(probmat))
  hda_probs[1] <- sum(probmat[lower.tri(probmat)])
  hda_probs[3] <- 1 - sum(hda_probs[1:2])
  
  sum((hda_probs - trgt_probs)^2)
  
}

# Estimate the expected goals from win-draw-lose probabilities. 
expg_from_probabilities <- function(probabilities){
  
  if (!is.matrix(probabilities)){
    probabilities <- matrix(probabilities, nrow=1, 
                            dimnames = list(NULL, names(probabilities)))
  }
  
  stopifnot(ncol(probabilities) == 3)
  
  expg <- matrix(ncol=2, nrow=nrow(probabilities))
  sq_errors <- numeric(nrow(probabilities))
  for (ii in 1:nrow(probabilities)){
    
    optim_res <- optim(c(0, 0), fn=lambda_sq_error, trgt_prob=probabilities[ii,])
    expg[ii,] <- exp(optim_res$par)
    sq_errors[ii] <- optim_res$value
  }
  
  out <- list(expg = expg, sq_errors=sq_errors)
  return(out)
}

I need help implementing this in javascript.
Can you write up a js version?
Thanks.

I am not familiar with javascript programming.