Adds Quantity Increment buttons that were depreciated as of WooCommerce 2.3

wc-quantity-increment.js

jQuery(function($) {

    // Quantity buttons
    $( 'div.quantity:not(.buttons_added), td.quantity:not(.buttons_added)' ).addClass( 'buttons_added' ).append( '<input type="button" value="+" class="plus" />' ).prepend( '<input type="button" value="-" class="minus" />' );

    $( document ).on( 'click', '.plus, .minus', function() {

        // Get values
        var $qty        = $( this ).closest( '.quantity' ).find( '.qty' ),
            currentVal  = parseFloat( $qty.val() ),
            max         = parseFloat( $qty.attr( 'max' ) ),
            min         = parseFloat( $qty.attr( 'min' ) ),
            step        = $qty.attr( 'step' );

        // Format values
        if ( ! currentVal || currentVal === '' || currentVal === 'NaN' ) currentVal = 0;
        if ( max === '' || max === 'NaN' ) max = '';
        if ( min === '' || min === 'NaN' ) min = 0;
        if ( step === 'any' || step === '' || step === undefined || parseFloat( step ) === 'NaN' ) step = 1;

        // Change the value
        if ( $( this ).is( '.plus' ) ) {

            if ( max && ( max == currentVal || currentVal > max ) ) {
                $qty.val( max );
            } else {
                $qty.val( currentVal + parseFloat( step ) );
            }

        } else {

            if ( min && ( min == currentVal || currentVal < min ) ) {
                $qty.val( min );
            } else if ( currentVal > 0 ) {
                $qty.val( currentVal - parseFloat( step ) );
            }

        }

        // Trigger change event
        $qty.trigger( 'change' );
    });

});