如何从数组中删除数值和空值？

Question

As part of my nightwatchjs testing, I have a dynamic array (in an object) that requires some tweaking.

My current array looks like this;

{ GenericColour:    [ 'Black',
     5059,
     'White',
     3610,
     'Grey',
     3281,
     'Blue',
     2131,
     'Silver',
     1408,
     'Red',
     1190,
     '',
     491,
     'Yellow',
     59,
     'Green',
     50,
     'Orange',
     31 ] }

but with it being dynamic, it might look slightly different the next time I run the test (a different colour might be added, or a current colour no longer listed, etc.).

What I would like to try and do is remove all the numbers, extra commas, etc. so I'm just left with an array reading (as per the example above);

['Black','White','Grey','Blue','Silver','Red','Yellow','Green','Orange']

Is there a way of doing this, either using JavaScript commands or regex?

Answer 1

You can use Array#filter , using the typeof operator to check if the element is a string.

 const arr = [ 'Black', 5059, 'White', 3610, 'Grey', 3281, 'Blue', 2131, 'Silver', 1408, 'Red', 1190, '', 491, 'Yellow', 59, 'Green', 50, 'Orange', 31 ]; const res = arr.filter(x => typeof x === 'string' && x); console.log(res);

Answer 2

You do that with the filter function:

obj = obj.GenericColour.filter(value => typeof value === 'string' )

Answer 3

    int numberArry = []
    arry.forEach(value => if(isNaN(value)) numberArry.push(value));

Answer 4

You can use array.prototype.filter to check for items in the array that are strings, removing all other items eg numbers. Check the link below for more info.

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/filter

it can be something like this:

array.filter((item) => typeof item === "string"); - this will return a new array with only the strings in the current array:

['Black','White','Grey','Blue','Silver','Red','Yellow','Green','Orange']

Answer 5

Simplest way would be passing isNaN to the filter method.

 const a = [ 'Black', 5059, 'White', 3610, 'Grey', 3281, 'Blue', 2131, 'Silver', 1408, 'Red', 1190, '', 491, 'Yellow', 59, 'Green', 50, 'Orange', 31 ]; const b = a.filter(isNaN); console.log(b);

Answer 6

One way is to filter based on checking length propterty.

For numbers and '' , the length value is 0 (false).

 const data = [ '', 'Black', 5059, 'White', 3610, 'Grey', 3281, 'Blue', 2131, 'Silver', 1408, 'Red', 1190, '', 491, 'Yellow', 59, 'Green', 50, 'Orange', 31 ]; const res = data.filter(str => str.length); console.log(res);

Answer 7

There are cases, where one can not reassign a filtered result to the original source reference. Like with...

const arr = [1, 2, 3]; arr = arr.filter(/* ... */);

... which will fail. One also might need to deal with properties which are not allowed to be written but of cause still can be mutated.

Then one needs a mutating remove approach based on a callback, exactly of the kind that filter asks for, where this callback function is the condition of whether to remove an array item or not.

 function removeEveryMatchingItemByCondition(arr, condition, target) { target = (target?? null); let idx = arr.length; const copy = Array.from(arr); // Processing the array from RIGHT to LEFT keeps the `idx` always in sync // with both related array items, the one of the mutated and also the one // of the unmutated version of the processed array reference. // Thus the `condition` always gets passed the unmutated shallow copy. while (idx) { if (arr.hasOwnProperty(--idx)) { // take a *sparse array* into account. // - keep processing the unmutated shallow copy by the `condition` method. // - arguments list...[elm, idx, arr]... invoked within `target` context. if (condition.call(target, copy[idx], idx, copy)) { arr.splice(idx, 1); // mutate processed array. } } } return arr; // return the mutated array reference. } const sampleObject = { GenericColour: [ 'Black', 5059, 'White', 3610, 'Grey', 3281, 'Blue', 2131, 'Silver', 1408, 'Red', 1190, '', 491, 'Yellow', 59, 'Green', 50, 'Orange', 31 ], }; removeEveryMatchingItemByCondition( sampleObject.GenericColour, // exactly what the OP was asking for in first place. (item => typeof item === 'number' || String(item).trim() === '') ); console.log(sampleObject); removeEveryMatchingItemByCondition( sampleObject.GenericColour, (item => typeof item === 'string') ); console.log(sampleObject);

 .as-console-wrapper { min-height: 100%;important: top; 0; }