jQuery Deferred isResolved() Method

What You’ll Learn

The isResolved() method returns true when a jQuery Deferred has completed successfully — and false while it is still pending or after a failure. This tutorial covers syntax, return values, five examples, comparisons with state(), and when not to poll this method.

Introduction

Callbacks like done() react when a Deferred succeeds. Sometimes you need a quick synchronous answer: has this task already completed successfully? isResolved() answers that question with a boolean — no callback registration required.

Use it for conditional debugging, branching in test helpers, or inspecting Deferred state at a known checkpoint. For production success handling, prefer done() or then() — they fire automatically when resolution happens, without polling.

Understanding the isResolved() Method

isResolved() is a state query on jQuery’s Deferred object. It returns true only when the Deferred has entered the resolved state via resolve(), a successful AJAX call, or a fulfilled promise in a chain.

It returns false when the Deferred is still pending (work not finished) or rejected (failure). A Deferred can only settle once — it never flips from resolved back to rejected.

📝 Syntax

General form of deferred.isResolved:

deferred.isResolved()

Return value

• true — the Deferred has been resolved successfully.
• false — the Deferred is still pending or was rejected.

Modern alternative (jQuery 3+)

if (dfd.state() === "resolved") {
  console.log("The operation succeeded");
}

Examples Gallery

Each example shows when isResolved() returns true or false. Use the Try-it links to run them interactively.

const dfd = $.Deferred();

dfd.resolve("Data loaded");

console.log(dfd.isResolved());  // true
console.log(dfd.state());       // "resolved"

true
"resolved"

const dfd = $.Deferred();

console.log(dfd.isResolved());  // false
console.log(dfd.state());       // "pending"

false
"pending"

const dfd = $.Deferred();

dfd.reject("Server error");

console.log(dfd.isResolved());  // false
console.log(dfd.isRejected());  // true
console.log(dfd.state());       // "rejected"

false
true
"rejected"

const dfd = $.Deferred();

console.log("before timeout:", dfd.isResolved());  // false

setTimeout(function () {
  dfd.resolve("Finished!");
}, 800);

dfd.done(function (value) {
  console.log("in done():", dfd.isResolved());  // true
  console.log("value:", value);
  console.log("state():", dfd.state());         // "resolved"
});

before timeout: false
in done(): true
value: Finished!
state(): "resolved"

function logStatus(dfd) {
  console.log("state():", dfd.state());
  console.log("isResolved():", dfd.isResolved());
  console.log('state === "resolved":', dfd.state() === "resolved");
}

const ok = $.Deferred().resolve("done");
logStatus(ok);

const failed = $.Deferred().reject("error");
logStatus(failed);

state(): resolved
isResolved(): true
state === "resolved": true

(resolved dfd — rejected dfd shows isResolved: false)

🚀 Use Cases

• Success state detection — confirm a Deferred succeeded before running follow-up logic.
• Conditional branching — choose different code paths in tests or debug utilities based on resolution.
• Dynamic UI updates — show content panels when state() is "resolved" after async UI loads.
• Logging — record resolution status alongside other Deferred metadata during diagnostics.
• Multi-task coordination — inspect individual Deferreds returned from $.when() after a batch completes.

📝 Notes

• isResolved() is deprecated in jQuery 3.0+ — use state() === "resolved" in new code.
• Never assume false means failure — it can also mean still pending.
• Prefer done() over polling isResolved() in production success handling.
• isResolved() and isRejected() are never both true on the same Deferred.
• For jqXHR from $.ajax(), the same state rules apply once the request completes.

💡 Best Practices