I am newbie in angular, facing one issue if somebody helps then it will be appreciable I have a array of objects like below
signals = [{
'signalID': '123'
},{
'signalID': '233'
},{
'signalID': '333'
},{
'signalID': '433'
},{
'signalID': '533'
},{
'signalID': '633'
},{
'signalID': '733'
}]
I have an object like below
signalOrder = {
333:1,
433:2,
533:3
}
i want to add an property to signals array as orderNo if signalId is matched in signalOrder object else orderNo should be null. Result expected :
signals = [{
'signalID': '123',
'orderNo':null
},{
'signalID': '233',
'orderNo':null
},{
'signalID': '333',
'orderNo':1
},{
'signalID': '433',
'orderNo':2
},{
'signalID': '533',
'orderNo':3
},{
'signalID': '633',
'orderNo':null
},{
'signalID': '733',
'orderNo':null
}]
I hope it should work with javascript map function but don't know how to use it.
You can do it like :
let signals = [{'signalID': '123'},{'signalID': '233'},{'signalID': '333'},{'signalID': '433'},{'signalID': '533'},{'signalID': '633'},{'signalID': '733'}];
let signalOrder = {333:1,433:2,533:3}
let mapped = signals.map(x=>{
return {
signalID:x.signalID,
orderNo:signalOrder[x.signalID]
}
})
console.log(mapped)You can use Array.map() to create the result you wish. For each signal item, we'll look up the orderNo in the signalOrder object. If not present, we'll set it to null.
const signals = [{ 'signalID': '123' },{ 'signalID': '233' },{ 'signalID': '333' },{ 'signalID': '433' },{ 'signalID': '533' },{ 'signalID': '633' },{ 'signalID': '733' }];
const signalOrder = {
333:1,
433:2,
533:3
}
const result = signals.map(({signalID}) => ({
signalID,
orderNo: signalOrder[signalID] || null
}))
console.log('Result:', result).as-console-wrapper { max-height: 100% !important; top: 0; }This has nothing to do with Angular or Typescript. It could be solved with vanilla JS Array methods.
Here is a method using Array#map, spread syntax, falsy test using OR ||. Attempting signalOrder[signal.signalID] would return undefined for unavailable properties, which is falsy. In these cases, null would be used.
Try the following
const signals = [{ 'signalID': '123' },{ 'signalID': '233' },{ 'signalID': '333' },{ 'signalID': '433' },{ 'signalID': '533' },{ 'signalID': '633' },{ 'signalID': '733' }]
const signalOrder = { 333:1, 433:2, 533:3 }
const result = signals.map(signal => ({
...signal,
orderNo: signalOrder[signal.signalID] || null
}));
console.log(result);.as-console-wrapper { max-height: 100% !important; top: 0; }