导致错误的数组元素顺序
Order of Array Elements Causing Error
我有两个数组。每个数组的元素如下所示:
allLabBranches = [{
"labbranchid": "1",
"labname": "Wahab Labs, Islampura Branch, Lahore",
"labtitle": "Wahab Labs Lahore",
"shortname": "WAHB",
"address": "56 Islampura, Lahore",
"landlineno": "04237940445",
"datecreated": "2016-03-11 11:00:00",
"createdbyname": "Jamshaid Sabir",
"createdbyuserid": "1",
"dateupdated": "2016-05-04 00:53:03",
"updatedbyname": "Jamshaid Sabir",
"updatedbyuserid": "1",
"clientgroups_clientgroupsid": "1",
"startdate": "2016-05-04"
}, {
"labbranchid": "2",
"labname": "Wahab Labs, Model Town Branch, Lahore",
"labtitle": "Wahab Labs Lahore",
"shortname": "WAHAB",
"address": "45 Model Town, Lahore",
"landlineno": "04237945485",
"datecreated": "2016-03-11 11:00:00",
"createdbyname": "Jamshaid Sabir",
"createdbyuserid": "1",
"dateupdated": "0000-00-00 00:00:00",
"updatedbyname": "",
"updatedbyuserid": "",
"clientgroups_clientgroupsid": "1",
"startdate": "0000-00-00"
}, {
"labbranchid": "3",
"labname": "Shahdara More Branch",
"labtitle": "Wahab Labs Lahore",
"shortname": "WAHAB",
"address": "Shahdara",
"landlineno": "04237933415",
"datecreated": "2016-03-11 11:48:15",
"createdbyname": "Jamshaid Sabir",
"createdbyuserid": "1",
"dateupdated": "0000-00-00 00:00:00",
"updatedbyname": "",
"updatedbyuserid": "",
"clientgroups_clientgroupsid": "1",
"startdate": "0000-00-00"
}, {
"labbranchid": "4",
"labname": "New Branch",
"labtitle": "Wahab Labs Lahore",
"shortname": "WAHB",
"address": "More Samanabad, Lahore",
"landlineno": "042361561",
"datecreated": "2016-03-11 11:52:06",
"createdbyname": "Jamshaid Sabir",
"createdbyuserid": "1",
"dateupdated": "2016-03-14 15:06:44",
"updatedbyname": "Jamshaid Sabir",
"updatedbyuserid": "1",
"clientgroups_clientgroupsid": "1",
"startdate": "2016-03-14"
}, {
"labbranchid": "5",
"labname": "Test Branch",
"labtitle": "xyz",
"shortname": "sfwe",
"address": "dsfasd",
"landlineno": "sdfasd",
"datecreated": "2016-03-12 00:14:11",
"createdbyname": "Jamshaid Sabir",
"createdbyuserid": "1",
"dateupdated": "2016-08-11 12:54:12",
"updatedbyname": "Jamshaid Sabir",
"updatedbyuserid": "1",
"clientgroups_clientgroupsid": "1",
"startdate": "2016-03-12"
}, {
"labbranchid": "6",
"labname": "Test Branch 2",
"labtitle": "asdfs",
"shortname": "asdfs",
"address": "asdf",
"landlineno": "asdf",
"datecreated": "2016-03-12 12:16:24",
"createdbyname": "Jamshaid Sabir",
"createdbyuserid": "1",
"dateupdated": "0000-00-00 00:00:00",
"updatedbyname": "",
"updatedbyuserid": "",
"clientgroups_clientgroupsid": "1",
"startdate": "2016-03-12"
}, {
"labbranchid": "7",
"labname": "Wahab Labs, Shahdara Branch, Lahore",
"labtitle": "Shahdara",
"shortname": "Shahdara",
"address": "Shahdara",
"landlineno": "0423744915",
"datecreated": "2016-08-11 12:56:27",
"createdbyname": "Jamshaid Sabir",
"createdbyuserid": "1",
"dateupdated": "2016-08-11 12:57:01",
"updatedbyname": "Jamshaid Sabir",
"updatedbyuserid": "1",
"clientgroups_clientgroupsid": "1",
"startdate": "2016-08-01"
}]
另一个数组元素是:
labsOfUser = [{
"userhasbranchid": "53",
"labbranches_labbranchid": "6",
"usersoflabs_userId": "9"
}, {
"userhasbranchid": "54",
"labbranches_labbranchid": "1",
"usersoflabs_userId": "9"
}, {
"userhasbranchid": "55",
"labbranches_labbranchid": "7",
"usersoflabs_userId": "9"
}, {
"userhasbranchid": "56",
"labbranches_labbranchid": "2",
"usersoflabs_userId": "9"
}]
现在我有一个选择多个框，我显示一些分支被选中，一些未被选中。代码如下:
function populateSelectedLabs() {
$('#labbranchids').empty();
if (allLabBranches.length >= labsOfUser.length) {
for (var i = 0; i < allLabBranches.length; i++) {
for (var j = 0; j < labsOfUser.length; j++) {
if (allLabBranches[i].labbranchid == labsOfUser[j].labbranches_labbranchid) {
$("#labbranchids").append("<option selected='selected' value='" + allLabBranches[i].labbranchid + "'>" + allLabBranches[i].labname + "</option>");
allLabBranches = jQuery.grep(allLabBranches, function(value) {
return value != allLabBranches[i];
});
} //end inner if
} //end inner loop
} //end outer loop
} //end if
for (var i = 0; i < allLabBranches.length; i++) {
$("#labbranchids").append("<option value='" + allLabBranches[i].labbranchid + "'>" + allLabBranches[i].labname + "</option>");
} //end for loop
} //end function
问题是数组元素比较忽略了数组中存在但位于数组中不同索引的元素。错误发生在以下代码行:
if(allLabBranches[i].labbranchid == labsOfUser[j].labbranches_labbranchid){
请帮助我知道如何比较两个数组中的所有元素?
某些项不匹配的原因是您在同一数组的循环内重新定义了allLabBranches，使其更短。
让我们假设在此更改之前以下内容为真:
labsOfUser[j-1].labbranches_labbranchid == allLabBranches[i+1].labbranchid
您希望在稍后的外部循环的下一次迭代中检测到这个相等。但由于重新赋值给allLabBranches，该值不再在索引i+1处，而是在索引i处。这个值在内部循环的剩余部分将不再匹配(因为匹配值在j-1)，因此i将在外部循环的下一次迭代中增加。因此，该值将永远不会被匹配。
您可以通过在allLabBranches数组中向后迭代来解决这个问题，但更好的方法是使用labsOfUser数组中的值创建一个散列。这将有更好的性能。
你可以这样做:
function populateSelectedLabs() {
$('#labbranchids').empty();
// create hash
var hash = {};
for (var j = 0; j < labsOfUser.length; j++) {
hash[labsOfUser[j].labbranches_labbranchid] = 1;
}
allLabBranches = jQuery.grep(allLabBranches, function(value) {
return hash[value.labbranchid];
}).concat(jQuery.grep(allLabBranches, function(value) {
return !hash[value.labbranchid];
}));
for (var i = 0; i < allLabBranches.length; i++) {
$("#labbranchids").append($('<option>')
.val(allLabBranches[i].labbranchid)
.text(allLabBranches[i].labname)
.attr('selected', hash[allLabBranches[i].labbranchid]));
}
}
如果目标浏览器支持ES6，那么你可以这样写:
function populateSelectedLabs() {
$('#labbranchids').empty();
var hash = new Set(labsOfUser.map( value => value.labbranches_labbranchid ));
allLabBranches.filter( value => hash.has(value.labbranchid) )
.concat(allLabBranches.filter( value => !hash.has(value.labbranchid) ))
.forEach( value =>
$("#labbranchids").append($('<option>')
.val(value.labbranchid)
.text(value.labname)
.attr('selected', hash.has(value.labbranchid)))
);
}
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