Why I'm getting an undefined? So I think this is a problem inside the arrow functions...
I need to amke it work by the arrow function inside the method say
const obj = {
a: 42,
say: () => {
console.log(this.a);
}
};
obj.say();
As other answers have explained, Arrow Functions don't have this values.
If you want similar concise syntax, you might want to try ES6 Method Definition syntax which does have this values, and is shorter than a whole function(){...}
var obj = {
a: 42,
say() {
console.log(this.a);
}
}
If you're structuring your app like this, it may make sense to go the whole hog and use ES6 Classes.
As a silly aside, it's also obviously possible that you can do the following:
var obj = {
a: 42,
say() {
console.log(obj.a); //obj not this
}
}
Don't use arrow function, since they don't have their own this. So, this (in case of arrow functions) will point to enclosing context.
var obj = {
a: 42,
say: function() {
console.log(this.a);
}
};
obj.say();
this and whose this you want to access in that function. If there is no need to access this and arguments then there is no reason not to use arrow function.
windowor the enclosing context doesn't haveafunctioninstead of an arrow function. In arrow functionsthisreferences the function. (tryconsole.log(this)).this. developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/…