过滤数据后在reactjs中设置状态

Question

I have this data which is coming as props .All items in this array has a date attached to it .I have aa date coming from a function and I want my current state to hold all data for the date I sent in the function .

I used filter in order to achieve this but it doesn't seem to be working . Here is the code for the same.

   updateWeather=(date)=>{
    console.log('date is',date);
     this.props.data.map((item)=>{
        console.log('item',item);
     })
    this.setState({

         today: this.props.data.filter( item =>item.date === date({
             date: item.date,
             time:item.time,
             temp: item.temp,
             humidity: item.humidity,
             weather: item.weather[0],
         }))
     });
 }`

Answer 1

This isn't going to work because you're comparing objects. Variables assigned objects hold references to values in memory. So even if the objects look the same, they aren't, unless they're told to point at the same reference like objA = objB which your example isn't doing.

You need to adjust your code to compare the individual properties of the objects.

You might want to grab the Object.keys() of each of the objects your comparing, then create a for loop that compares the values like:

const itemKeys = Object.keys(item);
const dateKeys = Object.keys(date);

for(let i = 0, n < itemKeys.length; i < n; i++){
    return item[itemKeys[i]] === date[dateKeys[i]]
}

Something along those lines.

Answer 2

By the way, if your object is not too big, and they don't contain nested objects, so you basically can convert them as string and then compare them, like so

const obj1 = {...};
const obj2 = {...};

JSON.stringify(obj1) === JSON.stringify(obj2);

So basically you are converting both object to be as string, but is you know that your object could have a nested object, so you shouldn't do this, instead iterate the tree object to check that both object has the same vale.