Underscore indexOf() not working in AngularJS {{ }} interpolation

Question

Say I've a simple array

$scope.array=[0,1,3,4,5,6];

and a view component where I want an ng-checked comparing with a vaule that must be in the array

`<ion-checkbox ng-checked="_.indexOf(array,1) !=-1"></ion-checkbox>`
`<ion-checkbox ng-checked="_.indexOf(array,2) !=-1"></ion-checkbox>`

I'm expecting the first checkbox being checked and not the second but they are both checked. Am I doing something wrong? thanks for help

Is there a variable named _ in your $scope? If not, _ is undefined. Why do you (try to) use underscore to do that in the first place? JS arrays have an indexOf method. — JB Nizet
– JB Nizet, Commented Aug 6, 2018 at 13:01
Yes I'm using underscore _ everywhere in app controllers.. I will try straight JS though — andrea.somovigo
– andrea.somovigo, Commented Aug 6, 2018 at 13:21
See AngularJS Developer Guide - AngularJS Expressions vs. JavaScript Expressions. — georgeawg
– georgeawg, Commented Aug 6, 2018 at 13:32
Show us the code of your controller, where you define the _ variable of the $scope then. — JB Nizet
– JB Nizet, Commented Aug 6, 2018 at 13:33
As you're probably using underscorejs or lodash, when you're using it from the methods in your javascript files it works. But once you're using inside the ng-checked it's looking for something like: $scope._.indexOf(...), if you want to keep using like this you can assign in your controller $scope._ = _;, but I prefer that you write a new method that receives your parameters and use the _ inside it. — Luiz Carlos
– Luiz Carlos, Commented Aug 6, 2018 at 13:38

7uc4 · Accepted Answer · 2018-08-06 14:35:07Z

2

AngularJS expressions are JavaScript-like code snippets that are mainly placed in interpolation bindings.

If you want to use Underscore, you should code a $scope function and call it:

Js:

$scope.exists = function(array, idx){
    return _.indexOf(array, idx) != -1;
}

HTML:

<ion-checkbox ng-checked="exists(array,1)"></ion-checkbox>

Alternatively, you might write

$scope._ = _;

From a Dependency Injection point of view you should provide Underscore as a constant.

edited Aug 6, 2018 at 14:35

answered Aug 6, 2018 at 14:08

7uc4

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Comments

Jit Dhar · Accepted Answer · 2018-08-06 14:12:52Z

1

<ion-checkbox ng-checked="array.indexOf(1)!=-1"></ion-checkbox>

You can try this one.

answered Aug 6, 2018 at 14:12

Jit Dhar

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1 Comment

andrea.somovigo Over a year ago

thanks to all, my question was over-simplified but you've cleared the concept. regading the usage of array.indexOf() or even _.indexOf() when comparing with the element with value 0 it always return false,. Said that I've worked around creating an object with string values, is there a safe way to match the 0 value with indexOf() ?

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