underscore.js , iterating over an array to list all index for a specific value

Question

I have an array in which I am tryingg to iterate to get ALL indexes when a true value is found for a key

    sheet.headings = [
      {
        "label": "SheetId",
        "access": "R",
        "hidden": true,
        "position": "left",
        "input_type": "text"
      },
      {
        "label": "Moteur Affichage",
        "access": "W",
        "hidden": false,
        "position": "left",
        "input_type": "text",
        "value_type": "text"
      },
      {
        "label": "Navigateur",
        "access": "W",
        "hidden": true,
        "position": "left",
        "input_type": "text",
        "value_type": "text"
      }
    ]

I can only get the first index, not all of the ( I should get [0,2]

    var column_hidden = _.findIndex(sheet.headings, function(col) {
      return col.hidden === true ;
    });

Carlos Mayo · Accepted Answer · 2015-09-22 11:06:30Z

1

Maybe you can achieve this using the map and filter functions of Array. Something like:

sheet.headings.map(function(e,i){
    if (e.hidden) return i;
}).filter(function(e){
    return typeof e != 'undefined';
})

First you get an array with the index than matches hidden==true and then you filter to remove the objects that are undefined.

answered Sep 22, 2015 at 11:06

Carlos Mayo

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1 Comment

user762579 Over a year ago

the 'ruby' way.. thanks a lot it's giving the expected result.... I was too narrow-minded, trying to use underscore.js functions....

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