Reports attempting to reassign variables declared with const.
✅ This rule is included in the ts untyped presets.
The const keyword creates a read-only reference to a value, preventing reassignment.
While properties of const objects and elements of const arrays can be mutated, the binding itself cannot be reassigned.
Attempting to reassign a const variable results in a runtime error.
Error ts(2588) ― Cannot assign to 'value' because it is a constant.
const
const result:any
result =
const getValue:any
getValue();
result=
const getOtherValue:any
getOtherValue();
Error ts(2588) ― Cannot assign to 'result' because it is a constant.
const
const counter:0
counter = 0;
counter++;
Error ts(2588) ― Cannot assign to 'counter' because it is a constant.
const {
const property:any
property } =
const object:any
object;
property="new value";
Error ts(2588) ― Cannot assign to 'property' because it is a constant.
for (const
const item:any
itemof
const items:any
items) {
item=
const processItem:any
processItem(
const item:any
item);
Error ts(2588) ― Cannot assign to 'item' because it is a constant.
}
let
let value:number
value = 1;
let value:number
value=2;
const
const object: {
value:number;
}
object = {
value: number
value: 1 };
const object: {
value:number;
}
object.
value: number
value=2;
const
const array:number[]
array = [1, 2, 3];
const array:number[]
array.
Array<number>.push(...items: number[]): number
Appends new elements to the end of an array, and returns the new length of the array.
@param ― items New elements to add to the array.
push(4);
const {
const property:any
property } =
const object:any
object;
var console:Console
The console module provides a simple debugging console that is similar to the
JavaScript console mechanism provided by web browsers.
The module exports two specific components:
A Console class with methods such as console.log(), console.error() and console.warn() that can be used to write to any Node.js stream.
A global console instance configured to write to process.stdout and
process.stderr. The global console can be used without importing the node:console module.
Warning: The global console object's methods are neither consistently
synchronous like the browser APIs they resemble, nor are they consistently
asynchronous like all other Node.js streams. See the note on process I/O for
more information.
Example using the global console:
console.log('hello world');
// Prints: hello world, to stdout
console.log('hello %s', 'world');
// Prints: hello world, to stdout
console.error(newError('Whoops, something bad happened'));
// Prints error message and stack trace to stderr:
// Error: Whoops, something bad happened
// at [eval]:5:15
// at Script.runInThisContext (node:vm:132:18)
// at Object.runInThisContext (node:vm:309:38)
// at node:internal/process/execution:77:19
// at [eval]-wrapper:6:22
// at evalScript (node:internal/process/execution:76:60)
// at node:internal/main/eval_string:23:3
const name = 'Will Robinson';
console.warn(`Danger ${name}! Danger!`);
// Prints: Danger Will Robinson! Danger!, to stderr
Example using the Console class:
const out = getStreamSomehow();
const err = getStreamSomehow();
const myConsole = newconsole.Console(out, err);
myConsole.log('hello world');
// Prints: hello world, to out
myConsole.log('hello %s', 'world');
// Prints: hello world, to out
myConsole.error(newError('Whoops, something bad happened'));
// Prints: [Error: Whoops, something bad happened], to err
Prints to stdout with newline. Multiple arguments can be passed, with the
first used as the primary message and all additional used as substitution
values similar to printf(3)
(the arguments are all passed to util.format()).
If your codebase relies on non-standard behavior that involves reassigning constant variables (which is highly discouraged), you might choose to disable this rule.
For example, if you target a legacy runtime with non-standard JavaScript semantics, standard practices may not apply to you.
