javascript Promise

window crypto

function convertStringToArrayBufferView(str){

    var bytes = new Uint8Array(str.length);

    for(var iii = 0 ; iii<str.lenght;iii++){
        bytes[iii] = str.charCodeAt(iii);
    }
    
    return bytes;
}

function convertArrayBufferToHexaDecimal(buffer){
    var data_view = new DataView(buffer);
    var iii,len,hex='',c;

    for(iii =0 ,len = data_view.byteLength;iii<len;iii++){
        c = data_view.getUint8(iii).toString(16);
        if(c.length<2){
            c= '0' +c;
        }

        hex += c;
    }

    return hex;
}

window.crypto.subtle.digest({name:"SHA-256"},convertStringToArrayBufferView("Hello World"))
.then(function(result){
    var hash_value = convertArrayBufferToHexaDecimal(result);

    console.log(hash_value);
})