Arrow functions have two syntactic forms for their function bodies. They may be defined with a block body (denoted by curly braces) () => { ... }
or with a single expression () => ...
, whose value is implicitly returned.
This rule can enforce or disallow the use of braces around arrow function body.
The rule takes one option, a string, which can be:
"always"
enforces braces around the function body"as-needed"
enforces no braces where they can be omitted (default)"never"
enforces no braces around the function body (constrains arrow functions to the role of returning an expression)
"arrow-body-style": ["error", "always"]
When the rule is set to "always"
the following patterns are considered problems:
/*eslint arrow-body-style: ["error", "always"]*/
/*eslint-env es6*/
let foo = () => 0;
The following patterns are not considered problems:
let foo = () => {
return 0;
};
let foo = (retv, name) => {
retv[name] = true;
return retv;
};
When the rule is set to "as-needed"
the following patterns are considered problems:
/*eslint arrow-body-style: ["error", "as-needed"]*/
/*eslint-env es6*/
let foo = () => {
return 0;
};
let foo = () => {
return {
bar: {
foo: 1,
bar: 2,
}
};
};
The following patterns are not considered problems:
/*eslint arrow-body-style: ["error", "as-needed"]*/
/*eslint-env es6*/
let foo = () => 0;
let foo = (retv, name) => {
retv[name] = true;
return retv;
};
let foo = () => ({
bar: {
foo: 1,
bar: 2,
}
});
let foo = () => { bar(); };
let foo = () => {};
let foo = () => { /* do nothing */ };
let foo = () => {
// do nothing.
};
When the rule is set to "never"
the following patterns are considered problems:
/*eslint arrow-body-style: ["error", "never"]*/
/*eslint-env es6*/
let foo = () => {
return 0;
};
let foo = (retv, name) => {
retv[name] = true;
return retv;
};
The following patterns are not considered problems:
/*eslint arrow-body-style: ["error", "as-needed"]*/
/*eslint-env es6*/
let foo = () => 0;
let foo = () => ({ foo: 0 });