eager() — svelte Function Reference

Architecture documentation for the eager() function in batch.js from the svelte codebase.

Function javascript ClientRuntime Reactivity calls 4 called by 1

Entity Profile

ClientRuntime→ Reactivity→ eager() — svelte Function Reference

Dependency Diagram

graph TD
  92a6b0f5_8829_33ec_80dd_aa943970a578["eager()"]
  d8e42d9d_2e3c_635c_19d3_b946a4341c0f["batch.js"]
  92a6b0f5_8829_33ec_80dd_aa943970a578 -->|defined in| d8e42d9d_2e3c_635c_19d3_b946a4341c0f
  a967b3b9_6263_60ec_74ff_b1889e66d284["fork()"]
  a967b3b9_6263_60ec_74ff_b1889e66d284 -->|calls| 92a6b0f5_8829_33ec_80dd_aa943970a578
  1e2f7428_6050_5cb7_69db_bf5db719f6d1["source()"]
  92a6b0f5_8829_33ec_80dd_aa943970a578 -->|calls| 1e2f7428_6050_5cb7_69db_bf5db719f6d1
  a08b6cc5_af73_1be4_d02f_3113cf8a8305["get()"]
  92a6b0f5_8829_33ec_80dd_aa943970a578 -->|calls| a08b6cc5_af73_1be4_d02f_3113cf8a8305
  80b95503_e5bc_4965_f8d9_a5ec40e8e1c2["eager_effect()"]
  92a6b0f5_8829_33ec_80dd_aa943970a578 -->|calls| 80b95503_e5bc_4965_f8d9_a5ec40e8e1c2
  2cab0f64_6d19_d981_66e2_d2555c252702["queue_micro_task()"]
  92a6b0f5_8829_33ec_80dd_aa943970a578 -->|calls| 2cab0f64_6d19_d981_66e2_d2555c252702
  style 92a6b0f5_8829_33ec_80dd_aa943970a578 fill:#6366f1,stroke:#818cf8,color:#fff

Relationship Graph

Source Code

packages/svelte/src/internal/client/reactivity/batch.js lines 886–922

export function eager(fn) {
	var version = source(0);
	var initial = true;
	var value = /** @type {T} */ (undefined);

	get(version);

	eager_effect(() => {
		if (initial) {
			// the first time this runs, we create an eager effect
			// that will run eagerly whenever the expression changes
			var previous_batch_values = batch_values;

			try {
				batch_values = null;
				value = fn();
			} finally {
				batch_values = previous_batch_values;
			}

			return;
		}

		// the second time this effect runs, it's to schedule a
		// `version` update. since this will recreate the effect,
		// we don't need to evaluate the expression here
		if (eager_versions.length === 0) {
			queue_micro_task(eager_flush);
		}

		eager_versions.push(version);
	});

	initial = false;

	return value;
}