An input.the valueAsDate method returns a Date object reflecting the input's current value. The displayed value follows the same format. To make it work:
new Date().toISOString().substr( 0, 10 ); new Date().toLocaleDateString(); input.valueAsDate; input.valueAsDate.toLocaleDateString(); new Date( input.valueAsDate ); new Date( input.valueAsDate ).toISOString().substr( 0, 10 );