Assign variable value of string

Question

I'm new to Javascript - I tried searching the web was not able this situation into context.

Here is the situation:

import * as People from ./People.json
import * as Education from ./Education.json
import * as Vehicle from ./Vehicle.json
...
function transpose(str : string) {
  let data = {};
  if(validate(str))  //validate function returns true if valid string
    data = str  //data takes in the string value and uses variable name
    runFile(data); //runFile expects data to be a JSON type
  ...
}

Essentially how do I convert str (string variable into a variable) if suppose str = "People" then data will be equal to the variable People or if str = "Vehicle" data will be Vehicle variable.

I know this can be done with a map of {"People": People, "Vehicle": Vehicle} it just seems like there should be a better way? I also looked into eval(str) but that doesn't seem to do the trick.

Any help would be appreciated.

Thanks

Only good way I see is to use an object and bracket notation. Eval almost never is a good idea. — Andrew Li
– Andrew Li, Commented Jul 10, 2018 at 0:47

mpen · Accepted Answer · 2018-07-10 00:50:09Z

3

A "map" really is the best way. Good news is that you can save a few keystrokes with shorthand property names (ES2015):

import * as People from ./People.json
import * as Education from ./Education.json
import * as Vehicle from ./Vehicle.json

const lookup = {People,Education,Vehicle}; // equivalent to {"People":People, ...}

function transpose(str : string) {
  let data = {};
  if(validate(str))  //validate function returns true if valid string
    data = lookup[str]  //data takes in the string value and uses variable name
    runFile(data); //runFile expects data to be a JSON type
  ...
}

answered Jul 10, 2018 at 0:50

mpen

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1 Comment

civic.sir Over a year ago

Ahh i was hoping this wouldn't be the solution.. thanks a lot @mpen +the pointer on ES2015

aaronedmistone · Accepted Answer · 2018-07-10 00:59:38Z

-1

Useful if you want to pass in JSON as a parameter to the transpose function.

function transpose(jsonObj, str) {
  let data = {};
  if(validate(str))
  {
    data = jsonObj[str];
    runFile(data); //runFile expects data to be a JSON type
  }
  ...
}

edited Jul 10, 2018 at 0:59

answered Jul 10, 2018 at 0:51

aaronedmistone

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