File input size validation

Hi
I used the link below for file validation.
https://preview.keenthemes.com/html/keen/docs/forms/formvalidation/advanced

How can I check the size of the input file as well?

var validator = FormValidation.formValidation(
form,
{
fields: {
'avatar': {
validators: {
notEmpty: {
message: 'Please select an image'
},
file: {
extension: 'jpg,jpeg,png',
type: 'image/jpeg,image/png',
message: 'The selected file is not valid'
},
}
},
},

plugins: {
trigger: new FormValidation.plugins.Trigger(),
bootstrap: new FormValidation.plugins.Bootstrap5({
rowSelector: '.fv-row',
eleInvalidClass: '',
eleValidClass: ''
})
}
}
);