Declare array of array in loop typescript

Question

On my app I have an object of dates which contains time array like Console log output is as follows

32: {
1514160000: Array [ 1200, 1500 ],
1514764800: Array [ 1200, 1500 ],
1515369600: Array [ 1200, 1500 ],
1515974400: Array [ 700, 1200, 1500 ],
1516579200: Array [ 700, 1200, 1500 ],
}

With this data I have implemented loop to create a new array of dates with time and worker id as follows ( similar to this )

1514160000 :[
1200 : [32,40,56],
1500 : [32,40],
],
1514764800: [
1200 : [32,40,56],
1500 : [32,40],
]

I have written following code for this where I want to create array of dates by dynamically assign dates and then create it an array again.

let allDates :any = [];
      for(let pid in this.allAvailableProviders)
      {
        console.log(pid);
        for(let slotDate in this.allAvailableProviders[pid]){
          if(!Array.isArray(allDates[slotDate])){
            let allDates[slotDate] :any = [];
          }
        }
      }

where allAvailableProviders is object

It gives me following error on ng serve

'=' expected

How can I do it ?

You have to assign the value, not store it in a variable, let allDates[slotDate] :any = []; should be allDates[slotDate] = []; to initialize an empty array at this index. — Supamiu
– Supamiu, Commented Dec 18, 2017 at 14:18

Joe · Accepted Answer · 2017-12-18 14:23:41Z

2

You are just initializing the array. There is no assignment or need for let:

    for(let slotDate in this.allAvailableProviders[pid]){
      if(!Array.isArray(allDates[slotDate])){
        allDates[slotDate] = [];
      }
    }

answered Dec 18, 2017 at 14:23

Joe

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1 Comment

Ruan Mendes Over a year ago

This fixes their compilation/parsing problem, but you should warn them that their code is not using the benefits of a type system.

Ruan Mendes · Accepted Answer · 2017-12-18 14:26:48Z

1

The let statement is followed by a variable name, not an expression.

You should just define your outer array as the right type, instead of any. You know it's an array of arrays.

  let allDates: any[][] = [];
  for(let pid in this.allAvailableProviders)
  {
    console.log(pid);
    for(let slotDate in this.allAvailableProviders[pid]){
      if(!Array.isArray(allDates[slotDate])){
        // You'd get an error if you assigned something that is not an array.
        // because you specified the type correctly
        allDates[slotDate] = [];
      }
    }
  }

answered Dec 18, 2017 at 14:26

Ruan Mendes

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4 Comments

Ramesh Rajendran Over a year ago

what is the difference between let allDates: any[][] = []; and let allDates: any = [];??

Ruan Mendes Over a year ago

const x: any[][] = 3 will fail compilation and so will const x: any[][] = [3]; Your code is saying that variable can take any type, my code is saying it has to be an array of arrays.

Ramesh Rajendran Over a year ago

Am asking what about const x: any= 3 vs const x: any[][] = [3]?? because it compiling as same right?

Ruan Mendes Over a year ago

@RameshRajendran Not sure what you are saying, I already explained to you that I'm adding actual types so that compiler can help you. const x: any[][] = [3]; will fail compilation because the compiler expects the array to contain other arrays, but you are putting in a number

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