CODEWITHSUNDEEP
javascriptreactjs
Silverfall05
Silverfall05

Reputation: 1127

React update struggle

I have struggle to understand how to update React state -> $push and $unshift..

My state looks like: data = { 2: [1, 2, 3], 7: [5, 3, 4] }

And I need to update records specific object key with variable and delete or add element into that array.. I've tried something like:

var elem_id = this.props.elem_id; var newArray = update(data, {elem_id: {$push: [4]}}); var newArray = update(data, {elem_id: {$unshift: [4]}});

But unsuccessfully what I'm doing wrong?

Thanks

Upvotes: 1

Views: 346

Answers (1)

Michelle Tilley
Michelle Tilley

Reputation: 159105

var newArray = update(data, {elem_id: {$push: [4]}});

will try to push 4 onto an array at the literal key elem_id; that is to say, elem_id is an object literal key, and is not replaced with the contents of the variable elem_id.

If you're using a transpiler that supports ES6's computed property syntax (like Babel), you could do the following:

var newArray = update(data, {[elem_id]: {$push: [4]}});

If you're not, you'll have to create the object and then set the operation:

var toUpdate = {};
toUpdate[elem_id] = {$push: [4]};
var newArray = update(data, toUpdate);

Upvotes: 1

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