CODEWITHSUNDEEP
javascript
Izio
Izio

Reputation: 398

How to add field to Object that may not yet exist?

I have a this._champ object (which is undefined by default).

I browser an array, and want to add this field with a value : this._champ[champ.name][ele.infos[0].StackableRangeName] = ele.value; but at the first iteration, [champ.name] is undefined, and [ele.infos[0].StackableRangeName] is always undefined, how to manage this?

I tried this ternary operator but it isn't working:

      this.champ[champ.name] != undefined ? this._champ[champ.name].push({ele.infos[0].StackableRangeName: ele.value}) : this._champ.push({champ.name: {ele.infos[0].StackableRangeName: ele.value}})

Upvotes: 0

Views: 642

Answers (2)

Barmar
Barmar

Reputation: 781721

This is a common idiom for initializing something with a default value if it's not yet set:

this.champ[champ.name] = this.champ[champ.name] || []

Upvotes: 3

Saeed
Saeed

Reputation: 5488

Just check for existence of the key. and then push value:

if(this.champ && !this.champ.hasOwnProperty(champ.name)) {
     this.champ[champ.name] = [];
}
this._champ[champ.name].push({ele.infos[0].StackableRangeName: ele.value});

Upvotes: 1

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