IconVault's JS Symbol Explorer covers the twelve well-known symbols that wire JavaScript's protocols together, each with a runnable example and a step-by-step flow diagram. Run Symbol.iterator to make a custom object work with for...of and spread, watch Symbol.toPrimitive decide how your object converts to strings versus numbers, override instanceof with Symbol.hasInstance, or hook String.prototype.replace through Symbol.replace. It is free and runs fully in your browser, and every example is copyable.

The explorer also covers the symbols people meet less often but hit in real code: Symbol.species controlling what map returns on subclasses, Symbol.isConcatSpreadable changing concat behavior, Symbol.unscopables hiding Array methods from with blocks, Symbol.dispose for explicit resource cleanup, Symbol.metadata for decorators, and the global registry pair Symbol.for/Symbol.keyFor.