Trailing commas in object literals are valid according to the ECMAScript 5 (and ECMAScript 3!) spec, however IE8 (when not in IE8 document mode) and below will throw an error when it encounters trailing commas in JavaScript.
var foo = {
bar: "baz",
qux: "quux",
};
This rule is aimed at detecting trailing commas in object literals. As such, it will warn whenever it encounters a trailing comma in an object literal.
The following are considered warnings:
var foo = {
bar: "baz",
qux: "quux",
};
var arr = [1,2,];
foo({
bar: "baz",
qux: "quux",
});
The following are okay and will not raise warnings:
var foo = {
bar: "baz",
qux: "quux"
};
var arr = [1,2];
foo({
bar: "baz",
qux: "quux"
});
If your code will not be run in IE8 or below (a NodeJS application, for example) and you'd prefer to allow trailing commas, turn this rule off.