return 42; // Return statement not inside a function
function f() {
'use strict';
// No more octal
var x = 042;
// Duplicate property
var y = { x: 1, x: 2 };
// With statement can't be used
with (z) {}
}
Unlike a typical code linter, this syntax validator does not care about coding styles and formatting.
If there is a syntax error, the sign will be shown in the left-side gutter. Placing the mouse cursor over that sign will reveal the complete error description.
For a command-line usage, check esvalidate from Esprima package (for Node.js). There is also a plugin for Grunt called grunt-jsvalidate. Ant users can take a look at an exemplary Ant task for syntax validation.
Esprima is created and mantained by Ariya Hidayat.