function Ninja() {
this.swung = false
this.swingSword = function() {
return !this.swung
}
}
function assert(value,text) {
if(value === true) {
console.log(text)
} else {
console.log('error')
}
}
Ninja.prototype.swingSword = function() {
return this.swung
}
const ninja = new Ninja()
ninja.swingSword = function() {
return '123'
}
assert(ninja.swingSword() === '123','called the instance method,not the prototype method')