JS to determine whether multiple pictures upload is empty and jpg format

JS to determine whether multiple pictures upload is empty and jpg format
<script language= "Web Effects" >

<!--

function filelast (filename) {<!--#得到文件后缀-->

Str=filename;

Strs=str.tolowercase ();

Lens=strs.length;

Return extname=strs.substring (Lens-4,lens);

function Frmcheck (theform) {

if (document.forall.name.value== "") {

Alert (' Please fill in the name!!! ');

Document.forAll.name.focus ();

return false;

}

if (document.forall.tel.value== "" && document.forAll.mobile.value = = "") {

Alert (' phone or cell phone fills in at least one!! ');

Document.forAll.tel.focus ();

return false;

}

if (theform.email.value!= "") {

if (!ismail (Theform.email.value)) {

Alert (' Your email format is not properly filled!!! ');

Theform.email.focus ();

return false;

}

}else{

Alert ("Please enter your email!!!");

Theform.email.focus ();

return false;

}

var jys1 = Document.getelementsbyname ("picture[]");

for (var i=0;i <jys1.length;i++) {

if (jys1[i].value== "" | | (jys1[i].value!= "" && filelast (Jys1[i].value)!= ". jpg")) {

Alert ("Please select a picture!! in. jpg format");

Jys1[i].focus ();

return false;

}

}
<script language= "JavaScript" >

<!--

function filelast (filename) {<!--#得到文件后缀-->

Str=filename;

Strs=str.tolowercase ();

Lens=strs.length;

Return extname=strs.substring (Lens-4,lens);

function Frmcheck (theform) {

if (document.forall.name.value== "") {

Alert (' Please fill in the name!!! ');

Document.forAll.name.focus ();

return false;

}

if (document.forall.tel.value== "" && document.forAll.mobile.value = = "") {

Alert (' phone or cell phone fills in at least one!! ');

Document.forAll.tel.focus ();

return false;

}

if (theform.email.value!= "") {

if (!ismail (Theform.email.value)) {

Alert (' Your email format is not properly filled!!! ');

Theform.email.focus ();

return false;

}

}else{

Alert ("Please enter your email!!!");

Theform.email.focus ();

return false;

}

var jys1 = Document.getelementsbyname ("picture[]");

for (var i=0;i <jys1.length;i++) {

if (jys1[i].value== "" | | (jys1[i].value!= "" && filelast (Jys1[i].value)!= ". jpg")) {

Alert ("Please select a picture!! in. jpg format");

Jys1[i].focus ();

return false;

}

}