Typescript conversion to boolean

Question

In Typescript I can do this:

var xxx : some_type;

if (xxx)
    foo();
else
    bar();

Here xxx will be treated as a boolean, regardless of its

Answer 1

if(xxx) {...} //read as TRUE if xxx is NOT undefined or null if(!xxx) {...} //read as TRUE if xxx IS undefined or null

For a string like 'true' or 'false': xxx.toLowerCase().trim() === 'true' ? true : false

so:

var zzz = 'true'; //string
var yyy = [];  //array

...

if(zzz.toLowerCase().trim() === 'true') { ... }  // quick string conversion

...

if(yyy ? true : false) { ... }  // quick any conversion - it's TRUE if it's not null or undefined

...

// in a catch-all function

if(toBoolean(zzz)) { ... }
if(toBoolean(yyy)) { ... }


toBoolean(xxx: any): boolean {
  if(xxx) {
    const xStr = xxx.toString().toLowerCase().trim();
    if(xStr === 'true' || x === 'false') {
      return xStr === 'true' ? true : false;
    } else {
      return xxx ? true : false;
    }
  } else {
    return false;
  }
}