TypeError: setting getter-only property "x"
The JavaScriptstrict mode-only exception "setting getter-only property" occurs when there is an attempt to set a new value to a property for which only agetter is specified, or when setting aprivate accessor property that similarly only has a getter defined.
Message
TypeError: Cannot set property x of #<Object> which has only a getter (V8-based)TypeError: '#x' was defined without a setter (V8-based)TypeError: setting getter-only property "x" (Firefox)TypeError: Attempted to assign to readonly property. (Safari)TypeError: Trying to access an undefined private setter (Safari)
Error type
TypeError instrict mode only.
What went wrong?
There is an attempt to set a new value to a property for which only agetter is specified.While this will be silently ignored in non-strict mode, it will throw aTypeError instrict mode. Classes are always in strict mode, so assigning to a getter-only private element always throws this error.
Examples
Property with no setter
The example below shows how to set a getter for a property.It doesn't specify asetter, so aTypeError will be thrown upon trying to set thetemperatureproperty to30. For more details see also theObject.defineProperty() page.
"use strict";function Archiver() { const temperature = null; Object.defineProperty(this, "temperature", { get() { console.log("get!"); return temperature; }, });}const arc = new Archiver();arc.temperature; // 'get!'arc.temperature = 30;// TypeError: setting getter-only property "temperature"To fix this error, you will either need to remove thearc.temperature = 30 line, which attempts toset the temperature property, or you will need to implement asetter for it, forexample like this:
"use strict";function Archiver() { let temperature = null; const archive = []; Object.defineProperty(this, "temperature", { get() { console.log("get!"); return temperature; }, set(value) { temperature = value; archive.push({ val: temperature }); }, }); this.getArchive = function () { return archive; };}const arc = new Archiver();arc.temperature; // 'get!'arc.temperature = 11;arc.temperature = 13;arc.getArchive(); // [{ val: 11 }, { val: 13 }]