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Is there a clean way to destructure the same variables from 2 similar objects in the same scope?
function(oldState, newState) {
let {foo, bar} = oldState;
// do stuff //
let {foo, bar} = newState; // illegal double declaration in same scope
{foo, bar} = newState; // illegal, not sure why
let {foo: foo1, bar: bar1} = newState; // legal but ugly
foo = newState.foo; // legal, but requires multiple lines
}
491
Nested Object and Array Destructuring Here's another example with an array of objects: You can destructure as deeply as you like: As you can see, keys a , b , and c are not implicitly defined, even though we pulled out nested values, firstElemOfC and remainingElementsOfC , from the array at c .
Destructuring is a JavaScript expression that allows us to extract data from arrays, objects, and maps and set them into new, distinct variables. Destructuring allows us to extract multiple properties, or items, from an array at a time.
To destructure an array in JavaScript, we use the square brackets [] to store the variable name which will be assigned to the name of the array storing the element.
JavaScript Object Destructuring is the syntax for extracting values from an object property and assigning them to a variable. The destructuring is also possible for JavaScript Arrays. By default, the object key name becomes the variable that holds the respective value.
You can wrap the assignment in parens to reassign the variables via destructuring. The reason this is necessary is because otherwise the { is assumed by the parser to begin a block rather than an object literal or assignment pattern. This blog post explains the situation in more detail.
function(oldState, newState) {
let {foo, bar} = oldState;
// do stuff //
({foo, bar} = newState);
}
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