JavaScript function with optional parameters [duplicate]

Answer 1

A good way to do this would be to use an object for all of the arguments. Something like:

function plotChart(options) {
  // Set defaults
  options.chart_type = options.chart_type || '1';

  // Check if each required option is set
  // Whatever is used by the data
}

Then when the function is called:

plotChart({
  data: 'some data',
  xlabel: 'some xlabel',
  ylabel: 'some ylabel',
  chart_type: '5' // This is optional
});