TypeScript - convert string to boolean

const text: string = 'true';

const value: boolean = text == 'true';

​

console.log(value); // true

function parseBoolean(text: string): boolean {

  const value = JSON.parse(text);

​

  if (typeof value != 'boolean') throw new Error('Incorrect type!');

​

  return value;

}

​

const text: string = 'true';

const value: boolean = parseBoolean(text);

​

console.log(value); // true

const truthExpression = /^(TRUE|True|true|YES|Yes|yes|ON|On|on|1|T|t|Y|y)$/g;

const falsyExpression = /^(FALSE|False|false|NO|No|no|OFF|Off|off|0|F|f|N|n)$/g;

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function parseBoolean(text: string): boolean {

  if (truthExpression.test(text)) return true;

​

  if (falsyExpression.test(text)) return false;

​

  throw new Error('Incorrect value!');

}

​

const text: string = 'true';

const value: boolean = parseBoolean(text);

​

console.log(value); // true

function parseBoolean(value: string | number | boolean): boolean {

  switch (value) {

    case 1:

    case true:

    case '1':

    case 'true':

    case 'True':

    case 'TRUE':

    case 'on':

    case 'On':

    case 'ON':

    case 'yes':

    case 'Yes':

    case 'YES':

    case 't':

    case 'T':

    case 'y':

    case 'Y':

      return true;

​

    case 0:

    case false:

    case '0':

    case 'false':

    case 'False':

    case 'FALSE':

    case 'off':

    case 'Off':

    case 'OFF':

    case 'no':

    case 'No':

    case 'NO':

    case 'f':

    case 'F':

    case 'n':

    case 'N':

      return false;

​

    default:

      throw new Error('Incorrect value!');

  }

}

​

const text: string = 'true';

const value: boolean = parseBoolean(text);

​

console.log(value); // true