您必须首先检索number列的当前值，以便能够在更新它之前加1并递增它。
要做到这一点，可以将当前的内容嵌套在请求的success函数中，以获取TotalViews的当前值：

function UpdateViewsinHow(param) {
    // first get the current value of TotalViews
    $.ajax({
        url: siteUrl + "/_api/web/lists/getbytitle('HowList')/items(" + param + ")?$select=TotalViews",
        method: "GET",
        headers: {
            "Accept": "application/json;odata=verbose",
            "X-RequestDigest": $("#__REQUESTDIGEST").val()
        },
        success: function (response) {
            var update = {
                __metadata: { 'type': 'SP.Data.HowListListItem' },
                
                // you may have to adjust this to get to the value of TotalViews
                // in the response, but it should be something close to this:
                TotalViews: response.d.TotalViews + 1

            };
            $.ajax({
                url: siteUrl + "/_api/web/lists/getbytitle('HowList')/items(" + param + ")",
                method: "PATCH",
                data: JSON.stringify(update),
                headers: {
                    "Accept": "application/json;odata=verbose",
                    "Content-Type": "application/json;odata=verbose",
                    "X-RequestDigest": $("#__REQUESTDIGEST").val(),
                    "IF-MATCH": "*",
                    "X-HTTPS-Method": "MERGE"
                },
                success: function (data) {
                    // confirm
                },
                error: function (error) {
                    alert("Error: " + JSON.stringify(error));
                }
            });
        },
        error: function (error) {
            alert("Error: " + JSON.stringify(error));
        }
    });
}