angularjs execute expression from variable

Question

How to execute expression from variable?

I need something like formula which depends from another inputs. For example my data:

    $scope.items = [{
    name: 'first',
    formula: '',
    value: 1,
    type: 'text',
},{
    name: 'second',
    formula: '',
    value: 2,
    type: 'text',
},{
    name: 'third',
    formula: '{first}+{second}',
    type: 'formula',
}];

and my view:

<ul>
<li ng-repeat="item in items">
    <div ng-switch on="item.type">
        <div ng-switch-when="text">
            <input type="text" ng-model="item.value" name="{{item.name}}">
        </div>
        <div ng-switch-when="formula">
            <span>{{item.formula}}</span>
        </div>
    </div>
</li>

I want that the result was 3 But it's {first}+{second} ofcourse

oh, forgot explain it! sorry I was going to grab values from input[name=first] and input[name=second] and apply sum for them — axon
– axon, Commented Sep 7, 2013 at 10:14
You would need to use a controller method to evaluate the formula as I have shown in the answer. — AlwaysALearner
– AlwaysALearner, Commented Sep 7, 2013 at 10:18

AlwaysALearner · Accepted Answer · 2013-09-07 10:33:15Z

1

<div ng-switch-when="formula">
    <span>
        {{getFormulaResult(item.formula)}}
    </span>
</div>

Controller method:

$scope.getFormulaResult = function(formula){
    var formulaSplits = formula.split("+");
    var left = formulaSplits[0];
    left = left.substr(1);
    left = left.substring(0, left.length-1);        
    var right = formulaSplits[1];
    right = right.substr(1);
    right = right.substring(0, right.length-1);
    var sum = 0;
    for(var i = 0; i < $scope.items.length; i++){
        if($scope.items[i].name == left || $scope.items[i].name == right){
            sum = sum + parseInt($scope.items[i].value, 10);
        }
    }
    return sum || 0;
}

edited Sep 7, 2013 at 10:33

answered Sep 7, 2013 at 10:12

AlwaysALearner

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1 Comment

axon Over a year ago

parseInt! How I could miss the sight of him! Thanks! I will try to modify your code for more difficult expressions

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