Using weighted variance in the love.plot function in R

Question

When using the love.plot function from cobalt package in R, there is an option to choose a parameter s.d.denom? I want to use the weighted variance in the denominator when calculating the standardized mean difference. Am I correct, if I choose s.d.denom="weighted"? What is the formula for weighted variance that is used in this function?

Following is the sample code.

  love.plot(
    covs, #Covariate matrix
    treat=mydata$grp,
    weights = list(wgtvar=mydata$wt]),
    thresholds=0.1 ,
    binary="std",
    shapes = c("circle filled"),
    line=FALSE,
    abs=TRUE,
    s.d.denom="weighted",
    grid=TRUE
  )