Javascript-在对象中动态创建数组并将其推送到

Question

How do I populate filters .

let filters = {};

To make it look like this:

filters = {
  color: ["Blue", "Black"],
  size: [70, 50]
};

So if I would have a function:

function populate(key, value) {
    //if key is color value gets pushed to filters.color
    //if key is size value gets pushed to filters.size
    //if any other key, create new property with new name
}

So doing this would result in a new array in filters:

populate(material, "plastic");

And filters would look like this:

filters = {
  color: ["Blue", "Black"],
  size: [70, 50],
  material: ["plastic"]
};

Answer 1

You can use in to check if the key exists in the object. Based on that push the value in the object array otherwise creates a new key with array value.

 let filters = {}; filters = { color: ["Blue", "Black"], size: [70, 50] }; function populate(key, value) { //if key is color value gets pushed to filters.color //if key is size value gets pushed to filters.size //if any other key, create new property with new name if(key in filters) filters[key].push(value); else filters[key] = [value]; } populate('material', "plastic"); console.log(filters); 

Answer 2

You could do something simple as this, where you check if the key exist and then push or assign .

array[key] ? array[key].push(value) : array[key] = [value];

Do note, you need to pass the key "material" as a string, and I as well recommend to pass the array too, to make the function more reusable.

 filters = { color: ["Blue", "Black"], size: [70, 50] }; function populate(a, k, v) { a[k] ? a[k].push(v) : a[k] = [v]; } populate(filters, "material", "plastic"); console.log(filters) 

Answer 3

You can use concat method of array if key present in filters Object otherwise it you will assign new array with new value.

DEMO

 var filters = { color: ["Blue", "Black"], size: [70, 50] }; function populate(key, value) { filters[key] = (filters[key]||[]).concat(value); } populate('material', "plastic"); populate('color', "Red"); populate('size',55); console.log(filters) 

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