how to make unit test to js code

hello everybody i have this javasicript code and I dont know how to make unit testing for it i need unit testing for the functions please help thank you all in advance Automated Testing The Unit Test Unit Testing Frameworks Assertions Test Functions, Cases, and Suites those above what I want to do anyone of them

var canvas = document.getElementById('stage'),
        word = document.getElementById('word'),
        letters = document.getElementById('letters'),
        wordToGuess,
        wordLength,
        badGuesses,
        correctGuesses;

function init() {
        var helptext = $('#helptext'),
                w = screen.availWidth <= 800 ? screen.availWidth : 800;
        
        $('#loading').hide();
        $('#play').css('display', 'inline-block').click(newGame);
        $('#clear').css('display', 'inline-block').click(resetScore);
        $('#help').click(function(e) {
                $('body').append('<div id="mask"></div>');
        helptext.show().css('margin-left', (w-300)/2 + 'px');
    });
        $('#close').click(function(e) {
                $('#mask').remove();
        helptext.hide();
    });
        
        if (screen.innerWidth >= 700) {
                canvas.getContext('2d').scale(1.5, 1.5);
        }
        
}


function newGame() {
        var placeholders = '',
                frag = document.createDocumentFragment(),
                abc = ['A','B','C','D','E','F','G','H','I','J','K','L','M','N','O','P','Q','R','S','T','U','V','W','X','Y','Z'];
        badGuesses = 0;
        correctGuesses = 0;
        wordToGuess = getWord();
        wordLength = wordToGuess.length;
        
        for (var i = 0; i < wordLength; i++) {
                placeholders += '_';
        }
        word.innerHTML = placeholders;  

                letters.innerHTML = '';
        for (i = 0; i < 26; i++) {
                var div = document.createElement('div');
                div.style.cursor = 'pointer';
                div.innerHTML = abc[i];
                div.onclick = getLetter;
                frag.appendChild(div);
        }
        letters.appendChild(frag);
        drawCanvas();
        window.scrollBy(0, 200);
        
}

function getLetter() {

        checkLetter(this.innerHTML);
        this.innerHTML = '&nbsp;';
        this.style.cursor = 'default';
        this.onclick = null;
 }
 
function checkLetter(letter) {
        var placeholders = word.innerHTML,
            wrongGuess = true;
                        placeholders = placeholders.split('');  
        for (var i = 0; i < wordLength; i++) {
                if (wordToGuess.charAt(i) == letter.toLowerCase()) {
                        placeholders[i] = letter;
                        wrongGuess = false;
                        correctGuesses++;
                        if (correctGuesses == wordLength) {
                                drawCanvas();
                        }
                }
        }
        if (wrongGuess) {
                badGuesses++;
                drawCanvas();
        }
        word.innerHTML = placeholders.join('');
                
}

function drawCanvas() {
        var c = canvas.getContext('2d');
                canvas.width = canvas.width;
        c.lineWidth = 10;
        c.strokeStyle = 'green';
        c.font = 'bold 24px Optimer, Arial, Helvetica, sans-serif';
        c.fillStyle = 'red';
        drawLine(c, [20,190], [180,190]);
        if (badGuesses > 0) {
                c.strokeStyle = '#A52A2A';
                drawLine(c, [30,185], [30,10]);
                if (badGuesses > 1) {
                        c.lineTo(150,10);
                        c.stroke();
                }
                if (badGuesses > 2) {
                        c.strokeStyle = 'black';
                        c.lineWidth = 3;
                        drawLine(c, [145,15], [145,30]);
                        c.beginPath();
                        c.moveTo(160, 45);
                        c.arc(145, 45, 15, 0, (Math.PI/180)*360);
                        c.stroke(); 
                }
                if (badGuesses > 3) {
                        drawLine(c, [145,60], [145,130]);
                }
                if (badGuesses > 4) {
                        drawLine(c, [145,80], [110,90]);
                }
                if (badGuesses > 5) {
                        drawLine(c, [145,80], [180,90]);
                }
                if (badGuesses > 6) {
                        drawLine(c, [145,130], [130,170]);
                }
                if (badGuesses > 7) {
                        drawLine(c, [145,130], [160,170]);
                        c.fillText('Game over', 45, 110);
                        letters.innerHTML = '';
                        setTimeout(showResult, 200);
                        localStorage.setItem('hangmanLose', 1 + parseInt(localStorage.getItem('hangmanLose')));
                        setTimeout(showScore, 2000);
                }
        }
        if (correctGuesses == wordLength) {
                letters.innerHTML = '';
                c.fillText('You won!', 45,110);
                localStorage.setItem('hangmanWin', 1 + parseInt(localStorage.getItem('hangmanWin')));
                setTimeout(showScore, 2000);
}
}



function drawLine(context, from, to) {
        context.beginPath();
        context.moveTo(from[0], from[1]);
        context.lineTo(to[0], to[1]);
        context.stroke();
}

function showResult() {
        var placeholders = word.innerHTML;
    placeholders = placeholders.split('');
        for (i = 0; i < wordLength; i++) {
                if (placeholders[i] == '_') {
                        placeholders[i] = '<span style="color:red">' + wordToGuess.charAt(i).toUpperCase() + '</span>';
                }
        }
        word.innerHTML = placeholders.join('');
}


function showScore() {
        var won = localStorage.getItem('hangmanWin'),
            lost = localStorage.getItem('hangmanLose'),
                c = canvas.getContext('2d');
        canvas.width = canvas.width;
        c.font = 'bold 24px Optimer, Arial, Helvetica, sans-serif';
    c.fillStyle = 'red';
        c.textAlign = 'center';
        c.fillText('YOUR SCORE', 100, 50);
        c.font = 'bold 18px Optimer, Arial, Helvetica, sans-serif';
        c.fillText('Won: ' + won + ' Lost: ' + lost, 100, 80);
}

function resetScore() {
        localStorage.setItem('hangmanWin', '0');
        localStorage.setItem('hangmanLose', '0');
        showScore();
}


function getWord() {
  var a = new Array('car','ball','cat','sea', 'the','of','and','a','to','in','is','you','that','it','he','was','for','on','are','as','with','his','they','I','at','be','this','have','from','or','one','had','by','word','but','not','what','all','were','we','when','your','can','said','there','use','an','each','which','she','do','how','their','if','will','up','other','about','out','many','then','them','these','so','some','her','would','make','like','him','into','time','has','look','two','more','write','go','see','number','no','way','could','people','my','than','first','water','been','call','who','oil','its','now','find','long','down','day','did','get','come','made','may','part');
  return a[parseInt(Math.random()* a.length)];
}