Parses Time String to JavaScript Date Object

parseTime.js

/**
	 * Parsing Time in String to a Date Obj
	 * @param timeString - time in String
	 * --> Acceptable Times - 
	 * 1,01,10,011,101,110,0111,1011,
	 * With AM/PM - 1p,01p,10p
	 * 
	 * @returns tempDateObj {Date} - Date Object that represents time String
	 */
	function parseTimeString(timeString) {
		
		var hour, minute,pm,
			tempDateObj = new Date(),
			num = timeString.replace(/[^0-9]/g, ''),
			numLength = num && num.length;
	 
		var stringContainsLetterP = timeString.match(/p/i) !== null;
		var stringContainsLetterA = timeString.match(/a/i) !== null;
		
		//setting tempDateObj to Mid-Night
		tempDateObj.setHours(0,0,0,0);
		
		// Parse for hour and minute
		switch(true) {
			case numLength >= 4:	
				hour = parseInt(num[0] + num[1], 10);
				minute = parseInt(num[2] + num[3], 10);
				break;
			case numLength === 3:
				hour = parseInt(num[0], 10);
				minute = parseInt(num[1] + num[2], 10);
				break;
			case numLength === 2:
			case numLength === 1:
				hour = parseInt(num[0] + (num[1] || ''), 10);
				minute = 0;
				break;
			// set default time as 12:00 PM when not able to parse
			default:
				hour = 12;
				minute = 0;
		}
		 
		// Finding AM/PM 
		pm =  stringContainsLetterP || ( !stringContainsLetterA && hour >= 12 && hour < 24 ) ;
		   
		// Make sure hour is in 24 hour format
		if( pm === true && hour >=0 && hour < 12 ) hour += 12; 
		if( !pm && hour == 12 ) hour = 0;  

		// This is the part of the validation
		// Keep within range
		// if hour is not valid or out of range --> default to 12:00PM
		if( hour < 0 || hour > 24){
			hour = 12;
			minute = 0;
		}
		//if minute is out of range --> set only minute to 0
		if( minute < 0 || minute > 59) minute = 0;
		
		//set Temp date obj to hours and minutes found out above by parsing time string
		tempDateObj.setHours(hour,minute);
		return tempDateObj;
	}