JavaScript Property with Three Dots (...)

Javascript Property with three dots (...)

That is not ES6 but has only been added in ECMAScript 2018.

It is called "Object Rest/Spread Properties" and is part of the Spread Syntax.

What are these three dots in React doing?

That's property spread notation. It was added in ES2018 (spread for arrays/iterables was earlier, ES2015), but it's been supported in React projects for a long time via transpilation (as "JSX spread attributes" even though you could do it elsewhere, too, not just attributes).

{...this.props} spreads out the "own" enumerable properties in props as discrete properties on the Modal element you're creating. For instance, if this.props contained a: 1 and b: 2, then

<Modal {...this.props} title='Modal heading' animation={false}>

would be the same as

<Modal a={this.props.a} b={this.props.b} title='Modal heading' animation={false}>

But it's dynamic, so whatever "own" properties are in props are included.

Since children is an "own" property in props, spread will include it. So if the component where this appears had child elements, they'll be passed on to Modal. Putting child elements between the opening tag and closing tags is just syntactic sugar — the good kind — for putting a children property in the opening tag. Example:

class Example extends React.Component {  render() {    const { className, children } = this.props;    return (      <div className={className}>      {children}      </div>    );  }}ReactDOM.render(  [    <Example className="first">      <span>Child in first</span>    </Example>,    <Example className="second" children={<span>Child in second</span>} />  ],  document.getElementById("root"));

.first {  color: green;}.second {  color: blue;}

<div id="root"></div>
<script src="https://cdnjs.cloudflare.com/ajax/libs/react/16.6.3/umd/react.production.min.js"></script><script src="https://cdnjs.cloudflare.com/ajax/libs/react-dom/16.6.3/umd/react-dom.production.min.js"></script>

What is the meaning of the three dots in the object?

Why that's referred to as spread syntax! :)

What do the three dots ... do in JavaScript

I think you need to read Iteration first;

let nums = [1,2,2,2,3,4,5];let setFromArray = new Set(nums);let arrayFromSet_spread = [...setFromArray];console.log("spread", arrayFromSet_spread); // here the spread will iterate over iteratable and return current value
//arrayFromSet can be written without spread like thislet arrayFromSet_forOf = [];for ( let el of setFromArray ) {  arrayFromSet_forOf.push(el)}console.log("forOf",arrayFromSet_forOf);

// and the most naive way to iterate :)let arrayFromSet_ManualIteration = [];let setFromArrayIterator = setFromArray[Symbol.iterator]();const firstElement = setFromArrayIterator.next();const secondElement = setFromArrayIterator.next();const thirdElement = setFromArrayIterator.next();const fourthElement = setFromArrayIterator.next();const fifthElement = setFromArrayIterator.next();const sixthElement = setFromArrayIterator.next();
arrayFromSet_ManualIteration.push(firstElement);arrayFromSet_ManualIteration.push(secondElement);arrayFromSet_ManualIteration.push(thirdElement);arrayFromSet_ManualIteration.push(fourthElement);arrayFromSet_ManualIteration.push(fifthElement);arrayFromSet_ManualIteration.push(sixthElement);
//you could just push values not the itaration object itself//arrayFromSet_ManualIteration.push(firstElement.value);//arrayFromSet_ManualIteration.push(secondElement.value);//arrayFromSet_ManualIteration.push(thirdElement.value);//arrayFromSet_ManualIteration.push(fourthElement.value);//arrayFromSet_ManualIteration.push(fifthElement.value);
console.log('ManualIteration full objects',arrayFromSet_ManualIteration);

Is it possible to use the spread operator (three dots) except specific keys?

you can use Destructuring_assignment to omit key2 and get the rest :

originalObject = {  key1: "",  key2: "",  key3: ""};
const { key2, ...clonedOriginalObject } = originalObject;
console.log(clonedOriginalObject);

javascript three dots syntax

That's the spread operator! It grabs all the properties from the object.

In that example, it'll copy the object without mutating it.

What is ... (3 dots) in javascript?

In that example, the ... is a Rest parameter, a syntax allows us to represent an indefinite number of arguments as an array.

It is somewhat similar (or not :), but it's not the same as the spread syntax.

In your example, the stores argument inside is an array. If function StoreMixin(...stores) is called like StoreMixin(1,2,3) then stores will be [1, 2, 3] and so on.

Dots in bracket to access nested property

It won't work automatically to pass a string like that to access the properties, you need to create a getter function like lodash _get and use it to find the value you need. And then write something like:

{{ _getAtr(element, col.id) }}

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