DayLight Savings

[Guest]

Hi,

I wrote a script to give me some pivots after the first 30 minutes. It works OK for the moment. However, I could not program it to incorporate the DayLight Savings issue. I am sure it will not work when the hours change.

What I simply do is to run a function if the current hour is greater or equal to 10.

I think that it can be coded but I dont know how. Can anybody help?

thanks in advance,
Izak

[eSignal_JasonK]

Hello Izak,

You're correct about the day light savings problem. JavaScript does not account for this automatically. The code example below will show you how to handle this. Basicly it checks to see if the current date is between the first Sunday of April and the last Sunday of October. If that condition is found to be true then we add 1 to the time zone offset. Hope this helps.

DayLightSavings.efs

/*****************************************************************
Provided By : eSignal. (c) Copyright 2004
*****************************************************************/

function preMain() {
    setPriceStudy(true);
    setStudyTitle("Day Light Savings ");
    setShowCursorLabel(false);
}


//var vTime = null;
var zoneOffset = null;
var NYzoneOffset = 5;
var NYfirstHr = 1030;
var firstHr = null;
var vDay = null;
var nDayLightSavings = 0;


function main() {
    var nState = getBarState();
    
    // set up target hour equal to 10:30am EST
    if (firstHr == null) {
        var x = new Date();
        vDay = x.getDate();
        nDayLightSavings = DayLightSavings(x);
        zoneOffset = (x.getTimezoneOffset()/60) + nDayLightSavings;
        firstHr = NYfirstHr - (zoneOffset - NYzoneOffset)*100;
        debugPrintln("10:30am EST is: " + firstHr + " my time.");
    }
    
    return;
}



function DayLightSavings(vDate) {
    /*** Daylight Saving Time (DST) begins at 2:00 a.m. on the first Sunday of April
         and reverts to Standard Time at 2:00 a.m. on the last Sunday of October. ***/

    var i = 0;
    var nDST = 0;
    var DSTstart, DSTend
    
    for (i = 1; i <= 31; ++i) {
        var tempDate = new Date("4/" + i + "/" + vDate.getFullYear());
        if (tempDate.getDay() == 0) {  // First Sunday of April
            DSTstart = tempDate;
            debugPrintln("First Sunday of April: " + DSTstart);
            i = 32;
        }
    }
    
    i = 31;
    for (i = 31; i > 0; --i) {
        var tempDate = new Date("10/" + i + "/" + vDate.getFullYear());
        if (tempDate.getDay() == 0) {  // Last Sunday of October
            DSTend = tempDate;
            debugPrintln("Last Sunday of October:  " + DSTend);
            i = 0;
        }
    }
    
    if (vDate >= DSTstart && vDate < DSTend) nDST = 1;

    return nDST;
} 

[Guest]

thank you so much Jason. The code has been very helpful.

I have another general question, if I may. In your code there is

for (i = 1; i <= 31; ++i) {
var tempDate = new Date(.....


When I don't use the "var" keyword there I get the same result. Actually, I seldomly use the var. Instead I just write the variable name make an assignment.

Does it cause any problems that I am not aware of? or do you use it for readability reasons?

Thank you so much again

Izak

[eSignal_JasonK]

Hello Izak,

JavaScript is soft-typed language, which means variables do not have to be explicitly defined with the var keyword. I use it anyway just out of habit, but it does help me quickly locate my variables when reading through larger formulas.

[Guest]

what is the point to use daylight savings? When the market's time change your computers' time change also.

Can anyone explain or am I missing something?

[ACM]

rookie2004
Arizona Hawaii and most of Indiana and many countries in Asia and in the southern hemisphere don't observe Daylight Saving Time.
Alex

[ACM]

In case someone is using the DayLightSavings.efs posted earlier in this thread here is a revised version of the script that takes into account the new Daylight Saving Time requirements
Alex

/*****************************************************************
Provided By : eSignal. (c) Copyright 2004
Modified by : Alexis C. Montenegro March 11 2007
*****************************************************************/

function preMain() {
    setPriceStudy(true);
    setStudyTitle("Daylight Saving ");
    setShowCursorLabel(false);
}

var zoneOffset = null;
var NYzoneOffset = 5;
var NYfirstHr = 1030;
var firstHr = null;
var vDay = null;
var nDayLightSavings = 0;

function main() {
    var nState = getBarState();
    
    // set up target hour equal to 10:30am EST
    if (firstHr == null) {
        var x = new Date();
        vDay = x.getDate();
        nDayLightSavings = DayLightSavings(x);
        zoneOffset = (x.getTimezoneOffset()/60) + nDayLightSavings;
        firstHr = NYfirstHr - (zoneOffset - NYzoneOffset)*100;
        debugPrintln("10:30am EST is: " + firstHr + " my time.");
    }
    
    return;
}


function DayLightSavings(vDate) {
    /*** Daylight Saving Time (DST) begins at 2:00 a.m. on the second Sunday of March
         and reverts to Standard Time at 2:00 a.m. on the first Sunday of November. ***/

    var i = 0;
    var nDST = 0;
    var DSTstart, DSTend;
    var Counter = 0;//added by ACM
    
    //begin section modified by ACM
    for (i = 1; i <= 31; ++i) {
        var tempDate = new Date("3/" + i + "/" + vDate.getFullYear());
        if (tempDate.getDay() == 0) { //if the day is a Sunday 
            Counter++;//increase the variable Counter by 1
            if(Counter==2){//Second Sunday of March
                DSTstart = tempDate;
                debugPrintln("Second Sunday of March: " + DSTstart);
                i=32
            }
        }
    }
    
    for (i = 1; i <= 31; ++i) {
        var tempDate = new Date("11/" + i + "/" + vDate.getFullYear());
        if (tempDate.getDay() == 0) {  //First Sunday in November
            DSTend = tempDate;
            debugPrintln("First Sunday of November: " + DSTend);
            i = 32;
        }
    }
    //end section modified by ACM
    
    if (vDate >= DSTstart && vDate < DSTend) nDST = 1;

    return nDST;
}