const toCamelCaseVar = (variable) => {
variable = variable.replace(/[\_|-](\w)/g, function (all, letter) {
return letter.toUpperCase();
});
return variable.slice(0, 1).toLowerCase() + variable.slice(1)
}
console.log(toCamelCaseVar('Foo_style_css')) // fooStyleCss
console.log(toCamelCaseVar('Foo-style-css')) // fooStyleCss