CODEWITHSUNDEEP
javascriptpolymerpolymer-1.0
Meisenmann
Meisenmann

Reputation: 129

Polymer: when is observer called

when is an observer in polymer 1.x called?

a-component

The a-component has a value property and an observer

properties: {
  aValue: {
    type: Number,
    observer: '_aValueChanged'
  }
}

b-component

The b-component has also a value property which can be used for two-way databinding.

properties: {
  bValue: {
    type: Number,
    notify: true
  }
}

It uses an a-component and two-way databinding to sync it's value.

<a-component id="a" a-value="{{bValue}}">

What happens if i change the vlaue of bValue

this.bValue = 1;
console.log(this.$.a.aValue);

Is it guaranteed that the observer of the a-compnent is executed before the console.log is executed?

Is it guaranteed that current value (1) is logged?

Thank you

Greets, Meisenmann

Upvotes: 0

Views: 193

Answers (1)

Amit K
Amit K

Reputation: 137

Yes, the observer is called before console.log() statement. And also console.log(this.$.a.aValue) will print "1". If the observer is not called, try using this.set("bValue", 1); instead of this.bValue = 1;

Upvotes: 1

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