disallow calling global object properties as functions (no-obj-calls)
The "extends": "eslint:recommended"
property in a configuration file enables this rule.
ECMAScript provides several global objects that are intended to be used as-is. Some of these objects look as if they could be constructors due their capitalization (such as Math
and JSON
) but will throw an error if you try to execute them as functions.
The ECMAScript 5 specification makes it clear that both Math
and JSON
cannot be invoked:
The Math object does not have a
[[Call]]
internal property; it is not possible to invoke the Math object as a function.
And the ECMAScript 2015 specification makes it clear that Reflect
cannot be invoked:
The Reflect object also does not have a
[[Call]]
internal method; it is not possible to invoke the Reflect object as a function.
Rule Details
This rule disallows calling the Math
, JSON
and Reflect
objects as functions.
Examples of incorrect code for this rule:
/*eslint no-obj-calls: "error"*/
var math = Math();
var json = JSON();
var reflect = Reflect();
Examples of correct code for this rule:
/*eslint no-obj-calls: "error"*/
function area(r) {
return Math.PI * r * r;
}
var object = JSON.parse("{}");
var value = Reflect.get({ x: 1, y: 2 }, "x");
Further Reading
Version
This rule was introduced in ESLint 0.0.9.