items: {JSON.stringify(object.items)}
``` ...the array being pushed to when the button is first clicked is the `[]` on the right-hand side of the assignment, but the resulting value of `object.array` is an empty state proxy. As a result, the pushed value will be discarded. You can fix this by separating it into two statements: ```js let object = { array: [0] }; // ---cut--- function add() { object.array ??= []; object.array.push(object.array.length); } ``` ### binding_property_non_reactive ``` `%binding%` is binding to a non-reactive property ``` ``` `%binding%` (%location%) is binding to a non-reactive property ``` ### console_log_state ``` Your `console.%method%` contained `$state` proxies. Consider using `$inspect(...)` or `$state.snapshot(...)` instead ``` When logging a [proxy](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Proxy), browser devtools will log the proxy itself rather than the value it represents. In the case of Svelte, the 'target' of a `$state` proxy might not resemble its current value, which can be confusing. The easiest way to log a value as it changes over time is to use the [`$inspect`](https://svelte.dev/docs/svelte/$inspect) rune. Alternatively, to log things on a one-off basis (for example, inside an event handler) you can use [`$state.snapshot`](https://svelte.dev/docs/svelte/$state#$state.snapshot) to take a snapshot of the current value. ### event_handler_invalid ``` %handler% should be a function. Did you mean to %suggestion%? ``` ### hydration_attribute_changed ``` The `%attribute%` attribute on `%html%` changed its value between server and client renders. The client value, `%value%`, will be ignored in favour of the server value ``` ### hydration_html_changed ``` The value of an `{@html ...}` block changed between server and client renders. The client value will be ignored in favour of the server value ``` ``` The value of an `{@html ...}` block %location% changed between server and client renders. The client value will be ignored in favour of the server value ``` ### hydration_mismatch ``` Hydration failed because the initial UI does not match what was rendered on the server ``` ``` Hydration failed because the initial UI does not match what was rendered on the server. The error occurred near %location% ``` ### invalid_raw_snippet_render ``` The `render` function passed to `createRawSnippet` should return HTML for a single element ``` ### legacy_recursive_reactive_block ``` Detected a migrated `$:` reactive block in `%filename%` that both accesses and updates the same reactive value. This may cause recursive updates when converted to an `$effect`. ``` ### lifecycle_double_unmount ``` Tried to unmount a component that was not mounted ``` ### ownership_invalid_binding ``` %parent% passed a value to %child% with `bind:`, but the value is owned by %owner%. Consider creating a binding between %owner% and %parent% ``` ### ownership_invalid_mutation ``` Mutating a value outside the component that created it is strongly discouraged. Consider passing values to child components with `bind:`, or use a callback instead ``` ``` %component% mutated a value owned by %owner%. This is strongly discouraged. Consider passing values to child components with `bind:`, or use a callback instead ``` ### reactive_declaration_non_reactive_property ``` A `$:` statement (%location%) read reactive state that was not visible to the compiler. Updates to this state will not cause the statement to re-run. The behaviour of this code will change if you migrate it to runes mode ``` In legacy mode, a `$:` [reactive statement](https://svelte.dev/docs/svelte/legacy-reactive-assignments) re-runs when the state it _references_ changes. This is determined at compile time, by analysing the code. In runes mode, effects and deriveds re-run when there are changes to the values that are read during the function's _execution_. Often, the result is the same — for example these can be considered equivalent: ```js let a = 1, b = 2, sum = 3; // ---cut--- $: sum = a + b; ``` ```js let a = 1, b = 2; // ---cut--- const sum = $derived(a + b); ``` In some cases — such as the one that triggered the above warning — they are _not_ the same: ```js let a = 1, b = 2, sum = 3; // ---cut--- const add = () => a + b; // the compiler can't 'see' that `sum` depends on `a` and `b`, but // they _would_ be read while executing the `$derived` version $: sum = add(); ``` Similarly, reactive properties of [deep state](https://svelte.dev/docs/svelte/$state#Deep-state) are not visible to the compiler. As such, changes to these properties will cause effects and deriveds to re-run but will _not_ cause `$:` statements to re-run. When you [migrate this component](https://svelte.dev/docs/svelte/v5-migration-guide) to runes mode, the behaviour will change accordingly. ### state_proxy_equality_mismatch ``` Reactive `$state(...)` proxies and the values they proxy have different identities. Because of this, comparisons with `%operator%` will produce unexpected results ``` `$state(...)` creates a [proxy](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Proxy) of the value it is passed. The proxy and the value have different identities, meaning equality checks will always return `false`: ```svelte ``` To resolve this, ensure you're comparing values where both values were created with `$state(...)`, or neither were. Note that `$state.raw(...)` will _not_ create a state proxy.