Javascript Array remove(elm)

Array.prototype.remove = function(elm){
 var arrAux = this

 var removeIndexA = this.indexOf(elm)
 var firstPart = this.splice(0,removeIndexA)

 var secondPart = this
 var removeIndexB = secondPart.indexOf(elm)

 var secondPart = this.splice(removeIndexB+1)

 return firstPart.concat(secondPart)
};

console.log(['a','b','c','d'].remove('a'))
console.log(['a','b','c','d'].remove('b'))
console.log(['a','b','c','d'].remove('c'))
console.log(['a','b','c','d'].remove('d'))