Script for divide split slices into arrays of certain length?

Try this.

#target photoshop 

var doc = activeDocument;
var oldPrefs = app.preferences.rulerUnits
app.preferences.rulerUnits = Units.PIXELS;
var dH = doc.height.value;
var splits = parseInt( dH/2000 + 1);

var sliceAmt = dH/splits

for (var i=0;i<splits;i++){
    if(i + 1 == splits){
        sliceImg (i*sliceAmt, 0, doc.height.value, doc.width.value)
        }
    sliceImg (i*sliceAmt, 0, (i+1) * sliceAmt, doc.width.value)
    }

app.preferences.rulerUnits = oldPrefs;

function sliceImg(topS, leftS, bottomS, rightS){
    var idMk = charIDToTypeID( "Mk  " );
        var desc4 = new ActionDescriptor();
        var idnull = charIDToTypeID( "null" );
            var ref1 = new ActionReference();
            var idslice = stringIDToTypeID( "slice" );
            ref1.putClass( idslice );
        desc4.putReference( idnull, ref1 );
        var idUsng = charIDToTypeID( "Usng" );
            var desc5 = new ActionDescriptor();
            var idType = charIDToTypeID( "Type" );
            var idsliceType = stringIDToTypeID( "sliceType" );
            var iduser = stringIDToTypeID( "user" );
            desc5.putEnumerated( idType, idsliceType, iduser );
            var idAt = charIDToTypeID( "At  " );
                var desc6 = new ActionDescriptor();
                var idTop = charIDToTypeID( "Top " );
                var idPxl = charIDToTypeID( "#Pxl" );
                desc6.putUnitDouble( idTop, idPxl, topS );
                var idLeft = charIDToTypeID( "Left" );
                var idPxl = charIDToTypeID( "#Pxl" );
                desc6.putUnitDouble( idLeft, idPxl, leftS );
                var idBtom = charIDToTypeID( "Btom" );
                var idPxl = charIDToTypeID( "#Pxl" );
                desc6.putUnitDouble( idBtom, idPxl, bottomS );
                var idRght = charIDToTypeID( "Rght" );
                var idPxl = charIDToTypeID( "#Pxl" );
                desc6.putUnitDouble( idRght, idPxl, rightS );
            var idRctn = charIDToTypeID( "Rctn" );
            desc5.putObject( idAt, idRctn, desc6 );
        var idslice = stringIDToTypeID( "slice" );
        desc4.putObject( idUsng, idslice, desc5 );
    executeAction( idMk, desc4, DialogModes.NO );    
    }