check whether an object is an array-like object
npm install @gyumeijie/is-array-like> check whether an object is an array-like object
``bash`
$ npm install @gyumeijie/is-array-like
`typescript`
isArrayLike(obj: any, similarity?: number): boolean
obj:
`
the object to be tested
similarity:
`
measure how much the obj is similar to the array object, there are three levels: 0, 1, 2:
0: return true iff obj has a valid length property, this is the default setting
1: return true iff obj has a valid length property and properties: [0, ..., length-1]
2: return true iff obj has and only has a valid length property and properties: [0, ..., length-1],strict array-like object
obj as such also called
> a strict array-like object can be safely converted to array using Array.from method
`javascript
let obj;
obj = {
0: 'zero',
2: 'two',
3: 'three',
length: 3,
};
Array.from(obj);
// ["zero", undefined, "two"] => missing one value, not safe
obj = {
0: 'zero',
2: 'two',
3: 'three',
length: -3,
};
Array.from(obj);
// [] => missing all values, not safe
obj = {
zero: 0,
one: 1,
two: 2,
length: 3,
};
Array.from(obj);
// [undefined, undefined, undefined] => missing all values, not safe
obj = {
0: 'zero',
1: 'one',
2: 'two',
name: 'obj',
length: 3,
};
Array.from(obj);
// ["zero", "one", "two"] => missing name property, not safe
obj = {
0: 'zero',
1: 'one',
2: 'two',
length: 3,
};
Array.from(obj);
// ["zero", "one", "two"] => containing all values, safely
`
`js
const isArrayLike = require('@gyumeijie/is-array-like');
// test truly array
isArrayLike([]); // true
isArrayLike([1, 2, 3, 4]); // true
// test non-array object
isArrayLike({}); // false
isArrayLike(1); // false
isArrayLike('string'); // false
isArrayLike(undefined); // false
isArrayLike(null); // false
isArrayLike(new Date()); // false
let fn = (arg1, arg2) => {};
isArrayLike(fn); // false
let re = /regexp/;
re.length = 1;
re[0] = 'zero';
isArrayLike(re); // false
let obj = {
0: 'zero',
2: 'two',
3: 'three',
length: 3,
};
isArrayLike(obj); // true
isArrayLike(obj, 1); // false
obj = {
0: 'zero',
1: 'one',
2: 'two',
length: 3,
};
isArrayLike(obj); // true
isArrayLike(obj, 1); // true
obj = {
zero: 0,
one: 1,
two: 2,
length: 3,
};
isArrayLike(obj); //true
isArrayLike(obj, 1); //false
obj = {
0: 'zero',
1: 'one',
2: 'two',
length: -3,
};
isArrayLike(obj); //false
isArrayLike(obj, 1); //false
obj = {
0: 'zero',
1: 'one',
2: 'two',
name: 'obj',
length: 3,
};
isArrayLike(obj); //true
isArrayLike(obj, 1); //true
isArrayLike(obj, 2); //false
``
MIT © Gyumeijie