| ⚠️ **You probably shouldn't be using this package directly.** | |
| Search for `createExPlatClient` within your codebase to find your platform's implementation. | |
| # ExPlat Client | |
| This is a standalone client for Automattic's ExPlat, allowing use of ExPlat in any Javascript context. | |
| ## Self-Contained | |
| `const exPlatClient = createExPlatClient(config)` | |
| - Dep injects outside parts so it can be fitted to any codebase. | |
| - Doesn't assume much of its environment. | |
| - No external dependencies or libs need. | |
| - Stores state in LocalStorage if available otherwise in memory. | |
| ## Type: `ExperimentAssignment` | |
| `ExperimentAssignment` represents an experiment assignment, as an experimenter you just need to look at `ExperimentAssignment.variationName`. | |
| - `variationName === null`: This means you should return the default experience. | |
| - `variationName !== null`: This means you should return the treatment experience. Currently `variationName` will always be `treatment`, but this may change. | |
| This type will likely be extended, it can also be missing in some API functions, particularly in the React side of things. A missing experiment assignment _does not_ mean the default experience, it means we do not have an assignment yet and if we can afford to wait we should, generally displaying a loading experience. | |
| ## API: `exPlatClient.loadExperimentAssignment` | |
| ### Type signature | |
| `loadExperimentAssignment: (experimentName: string) => Promise<ExperimentAssignment>` | |
| ### Usage | |
| ``` | |
| const experimentAssignment = await loadExperimentAssignment('experiment_name') | |
| ``` | |
| - Call as many times and as much as you like, we manage the state and requests. | |
| - Use earlier in code to prefetch the experimentAssignment. | |
| - Try not to use it in SSR contexts, but it will not crash anything if it does and we will log these cases. | |
| - Respects the server returned TTL (3600 seconds in production at the time of writing). | |
| - The promise non-resolution/resolution is the loading state. | |
| - Designed to never throw | |
| ## API: `exPlatClient.dangerouslyGetExperimentAssignment` | |
| ### Type signature | |
| `dangerouslyGetExperimentAssignment: ( experimentName: string ) => ExperimentAssignment` | |
| ### Usage | |
| ``` | |
| // An experiment MUST be loaded beforehand: | |
| loadExperimentAssignment( 'experiment_name' ); | |
| // Then, significantly enough in the future for the loading to have occurred: | |
| const experimentAssignment = dangerouslyGetExperimentAssignment( 'experiment_name' ); | |
| ``` | |
| This is an "asyncronous escape hatch", allowing you to use ExPlat in more synchronous code such as within `/lib`. | |
| - Gets but won't load/assign an experiment assignment. | |
| - ~~MUST be wrapped in a try-catch block.~~ It now logs and won't throw. | |
| - Named so it is easy to spot in a code review. | |
| Checklist for use: | |
| - [ ] Does `loadExperimentAssignment` get called before `dangerouslyGetExperimentAssignment` gets called. | |
| - [ ] Does `loadExperimentAssignment` get called significantly before it (minimum 2 seconds looking at perf data, 5-10 seconds is best). | |
| - [ ] ~~Is `dangerouslyGetExperimentAssignment` wrapped in a try-catch block~~ | |
| - [ ] Are there no `console.log` errors being emitted? | |