javascript - Cannot read property push of null - Stack Overflow

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while pushing an element for the first time to a child array which is null,I'm getting this error "Cannot read property push of null" But the element gets pushed,and the second time I do everything goes fine.It gets added to the array

this.group.departmentsList.push({
    name: group.newCategoryName,
    sortOrder: group.departmentsList.length,
    type: "category"
});

group contains the data and departmentList is the child array which is declared like this:

 $scope.parentDepartment = [
    {
        departmentsList: [{}]
    }
];

while pushing an element for the first time to a child array which is null,I'm getting this error "Cannot read property push of null" But the element gets pushed,and the second time I do everything goes fine.It gets added to the array

this.group.departmentsList.push({
    name: group.newCategoryName,
    sortOrder: group.departmentsList.length,
    type: "category"
});

group contains the data and departmentList is the child array which is declared like this:

 $scope.parentDepartment = [
    {
        departmentsList: [{}]
    }
];

• javascript
• arrays
• angularjs-scope

Share Improve this question Follow edited Oct 9, 2014 at 7:53 dfsq 193k2626 gold badges242242 silver badges259259 bronze badges asked Oct 9, 2014 at 7:50 forgottoflyforgottofly 2,7191212 gold badges5454 silver badges9696 bronze badges

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1 Answer 1

Sorted by: Reset to default 25

Well don't push to nonexistent array maybe? You can explicitly check if it's not null and create one if needed:

this.group.departmentsList = this.group.departmentsList || [];
this.group.departmentsList.push({
    name: group.newCategoryName,
    sortOrder: group.departmentsList.length,
    type: "category"
});

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