Rest operator
In JavaScript, rest syntax uses three dots to collect remaining function arguments, array elements, or object properties into a single binding.
Essential TypeScript 5, Third Edition
A rest parameter collects an arbitrary number of function arguments into a single parameter value.
- How it is used
- Allows functions to accept extra arguments without declaring a separate parameter for each one.
- How deep it goes
- Explains syntax, last-position and single-parameter rules, array initialization, typed values, and calls with varying argument counts.
- Examples
- Works through price summation with mixed JavaScript values and a TypeScript tax calculation with zero or several extra fees.
- What you can do after
- Build it from scratch: define a TypeScript function that collects and totals a variable number of typed extra arguments.
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Secrets of the JavaScript Ninja, Second Edition
A function parameter syntax that collects remaining supplied arguments into a single array-like value.
- How it is used
- Collects excess function-call arguments under one named parameter so a function can process a variable number of values.
- How deep it goes
- Explains the syntax, array collection, and final-parameter restriction, and demonstrates sorting without detailing browser compatibility.
- Examples
- Demonstrates `multiMax(3, 1, 2, 3)`, sorting the remaining values, and multiplying the first by the largest.
- What you can do after
- Apply `...name` to collect remaining arguments into an array and process them inside a function.
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Get Programming with JavaScript Next: New features of ECMAScript 2015, 2016, and beyond
A function parameter in JavaScript syntax that collects the remaining arguments into a single array binding and must appear last in the parameter list.
- How it is used
- Collects variable numbers of function arguments for array processing or forwarding through a wrapper.
- How deep it goes
- Explains the syntax, array binding, last-position rule, and forwarding pattern through short worked examples.
- Examples
- Uses family and property-selection functions, an image-processing wrapper, and a CSS-class exercise.
- What you can do after
- Apply it via JavaScript rest parameters to collect extra arguments and pass them through a logging wrapper.
Related concepts
- argumentsalternative to · The JavaScript arguments object is an array-like object available inside non-arrow functions that exposes the values passed to the current function invocation.
- arrayproduces · An array is an indexed, ordered collection of elements arranged in one or more dimensions, with elements accessed by position.
- functionpart of · A function is a callable program unit that performs an operation, may accept inputs, and can produce a result or side effect.
- spread operatorcontrasts with · A spread operator is syntax that unpacks a collection’s elements or an object’s properties into individual values within an expression or function call.
- function argumentuses · A function argument is a value or expression supplied when a function or method is invoked, providing input to the called operation.
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