node.js - Delete a key under a condition in Javascript object - Stack Overflow

admin管理员组

文章数量:1023120

I need to write a removeVowelKeys function that takes an object and removes all keys that begin with a vowel. The register does not matter.

For example, I have an object

const vowelsObj = {
  alarm: 'hello',
  chip: 100,
  isValid: false,
  Advice: 'Learn it hard',
  onClick: 'make it great again',
}

The result of a function's work should look like this:

vowelsObj === {
  chip: 100,
}

This is what I've already written

function removeVowelKeys(object) {
  const num = Object.keys(object);

  for( let i = 0; i < num.length; i++) {
    for (let key in object) {
    if (key.startsWith('a'||'e'||'i'||'o'||'u'||'y')) {
      delete object[key];
        }
    }
    }
    return object;
}

but it removes only the first field that starts with a vowel and the others stay. Any ideas how it can be done?

I need to write a removeVowelKeys function that takes an object and removes all keys that begin with a vowel. The register does not matter.

For example, I have an object

const vowelsObj = {
  alarm: 'hello',
  chip: 100,
  isValid: false,
  Advice: 'Learn it hard',
  onClick: 'make it great again',
}

The result of a function's work should look like this:

vowelsObj === {
  chip: 100,
}

This is what I've already written

function removeVowelKeys(object) {
  const num = Object.keys(object);

  for( let i = 0; i < num.length; i++) {
    for (let key in object) {
    if (key.startsWith('a'||'e'||'i'||'o'||'u'||'y')) {
      delete object[key];
        }
    }
    }
    return object;
}

but it removes only the first field that starts with a vowel and the others stay. Any ideas how it can be done?

• javascript
• node.js
• loops
• object
• conditional-statements

Share Improve this question Follow asked Dec 7, 2020 at 21:13 Anna HarshynaAnna Harshyna 9322 silver badges88 bronze badges 3

• 2 key.startsWith('a'||'e'||'i'||'o'||'u'||'y')) That doesn't do what you think it does,.. 'a'||'e'||'i'||'o'||'u'||'y' = 'a', IOW: your code does -> key.startsWith('a') – Keith Commented Dec 7, 2020 at 21:25
• Try this ['a','e','i','o','u','y'].includes(key.charAt(0).toLowerCase()) in your if statement. – ptothep Commented Dec 7, 2020 at 21:26
• Programing language ain't understand key.startsWith('a' || 'b' || 'c') like human, you should translate it to key.startsWith('a') || key.startsWith('b') || key.startsWith('c'); Or just ['a', 'b', 'c'].includes(key[0].toLowerCase()); Or, if you prefer a more pact way, const removeVowelKeys = object => Object.fromEntries(Object.entries(object).filter(pair => !['a','e','i','o','u','y'].includes(pair[0][0].toLowerCase()))), this line of function will destruct object as key-value pair, then just filter out key that is vowel, and return a new constructed object – zmou-d Commented Dec 7, 2020 at 23:21

Add a ment  | 

3 Answers 3

Sorted by: Reset to default 2

You could use the regex /^[aeiouy]/. The ^ in the regex matches the start of the string [aeiouy] matches one of a, e, i, o, u, or y. To match case in-sensitive (ignore character casing) add the i flag. eg. /^[aeiouy]/i

const vowelsObj = {
  alarm: 'hello',
  chip: 100,
  isValid: false,
  Advice: 'Learn it hard',
  onClick: 'make it great again',
}

function removeVowelKeys(object) {
  for (let key in object) {
    if (key.match(/^[aeiouy]/)) {
      delete object[key];
    }
  }
  return object;
}


removeVowelKeys(vowelsObj);
console.log(vowelsObj);

I've kept removeVowelKeys similar to what you already had. However delete mutates the argument. If you don't want this, copy the properties that you do want to a new object instead of deleting from the original.

const copy = {};
for (let key in object) {
  if (!key.match(/^[aeiouy]/)) { // <- added ! to invert the if-statement
    copy[key] = object[key];
  }
}
return copy;

You are simply including an extra for loop outside looping through the keys which are not needed and using includes will be helpful than repeating the startsWith for each and every character.

const vowelsObj = {
    alarm: 'hello',
    chip: 100,
    isValid: false,
    Advice: 'Learn it hard',
    onClick: 'make it great again',
}

function removeVowelKeys(object) {
    const updatedResult = Object.keys(object).reduce((updatedResult, key) => {
        const char = (typeof(key) === 'string' && key.trim().length > 0)? key.toLowerCase().charAt(0) : '';
        if (!['a', 'e' , 'i' ,'o' , 'u' ,'y'].includes(char)){
            updatedResult[key] = object[key];
        }
        return updatedResult;
    }, {})
    return updatedResult;
}

console.log(removeVowelKeys(vowelsObj));

You have to use individual .startsWith calls for each character. Also you need to transform the key to lowercase to remove the uppercase keys.

const vowelsObj = {
  alarm: 'hello',
  chip: 100,
  isValid: false,
  Advice: 'Learn it hard',
  onClick: 'make it great again',
}

function removeVowelKeys(object) {
  const num = Object.keys(object);

  for( let i = 0; i < num.length; i++) {
    for (let key in object) {
      const lowercaseKey = key.toLowerCase()
      if (
        lowercaseKey.startsWith('a') || lowercaseKey.startsWith('e')
          || lowercaseKey.startsWith('i') || lowercaseKey.startsWith('o')
          || lowercaseKey.startsWith('u') || lowercaseKey.startsWith('y')
      ) {
        delete object[key];
      }
    }
  }
    return object;
}

console.log(
  removeVowelKeys(vowelsObj)
)

I need to write a removeVowelKeys function that takes an object and removes all keys that begin with a vowel. The register does not matter.

For example, I have an object

const vowelsObj = {
  alarm: 'hello',
  chip: 100,
  isValid: false,
  Advice: 'Learn it hard',
  onClick: 'make it great again',
}

The result of a function's work should look like this:

vowelsObj === {
  chip: 100,
}

This is what I've already written

function removeVowelKeys(object) {
  const num = Object.keys(object);

  for( let i = 0; i < num.length; i++) {
    for (let key in object) {
    if (key.startsWith('a'||'e'||'i'||'o'||'u'||'y')) {
      delete object[key];
        }
    }
    }
    return object;
}

but it removes only the first field that starts with a vowel and the others stay. Any ideas how it can be done?

I need to write a removeVowelKeys function that takes an object and removes all keys that begin with a vowel. The register does not matter.

For example, I have an object

const vowelsObj = {
  alarm: 'hello',
  chip: 100,
  isValid: false,
  Advice: 'Learn it hard',
  onClick: 'make it great again',
}

The result of a function's work should look like this:

vowelsObj === {
  chip: 100,
}

This is what I've already written

function removeVowelKeys(object) {
  const num = Object.keys(object);

  for( let i = 0; i < num.length; i++) {
    for (let key in object) {
    if (key.startsWith('a'||'e'||'i'||'o'||'u'||'y')) {
      delete object[key];
        }
    }
    }
    return object;
}

but it removes only the first field that starts with a vowel and the others stay. Any ideas how it can be done?

• javascript
• node.js
• loops
• object
• conditional-statements

Share Improve this question Follow asked Dec 7, 2020 at 21:13 Anna HarshynaAnna Harshyna 9322 silver badges88 bronze badges 3

• 2 key.startsWith('a'||'e'||'i'||'o'||'u'||'y')) That doesn't do what you think it does,.. 'a'||'e'||'i'||'o'||'u'||'y' = 'a', IOW: your code does -> key.startsWith('a') – Keith Commented Dec 7, 2020 at 21:25
• Try this ['a','e','i','o','u','y'].includes(key.charAt(0).toLowerCase()) in your if statement. – ptothep Commented Dec 7, 2020 at 21:26
• Programing language ain't understand key.startsWith('a' || 'b' || 'c') like human, you should translate it to key.startsWith('a') || key.startsWith('b') || key.startsWith('c'); Or just ['a', 'b', 'c'].includes(key[0].toLowerCase()); Or, if you prefer a more pact way, const removeVowelKeys = object => Object.fromEntries(Object.entries(object).filter(pair => !['a','e','i','o','u','y'].includes(pair[0][0].toLowerCase()))), this line of function will destruct object as key-value pair, then just filter out key that is vowel, and return a new constructed object – zmou-d Commented Dec 7, 2020 at 23:21

Add a ment  | 

3 Answers 3

Sorted by: Reset to default 2

You could use the regex /^[aeiouy]/. The ^ in the regex matches the start of the string [aeiouy] matches one of a, e, i, o, u, or y. To match case in-sensitive (ignore character casing) add the i flag. eg. /^[aeiouy]/i

const vowelsObj = {
  alarm: 'hello',
  chip: 100,
  isValid: false,
  Advice: 'Learn it hard',
  onClick: 'make it great again',
}

function removeVowelKeys(object) {
  for (let key in object) {
    if (key.match(/^[aeiouy]/)) {
      delete object[key];
    }
  }
  return object;
}


removeVowelKeys(vowelsObj);
console.log(vowelsObj);

I've kept removeVowelKeys similar to what you already had. However delete mutates the argument. If you don't want this, copy the properties that you do want to a new object instead of deleting from the original.

const copy = {};
for (let key in object) {
  if (!key.match(/^[aeiouy]/)) { // <- added ! to invert the if-statement
    copy[key] = object[key];
  }
}
return copy;

You are simply including an extra for loop outside looping through the keys which are not needed and using includes will be helpful than repeating the startsWith for each and every character.

const vowelsObj = {
    alarm: 'hello',
    chip: 100,
    isValid: false,
    Advice: 'Learn it hard',
    onClick: 'make it great again',
}

function removeVowelKeys(object) {
    const updatedResult = Object.keys(object).reduce((updatedResult, key) => {
        const char = (typeof(key) === 'string' && key.trim().length > 0)? key.toLowerCase().charAt(0) : '';
        if (!['a', 'e' , 'i' ,'o' , 'u' ,'y'].includes(char)){
            updatedResult[key] = object[key];
        }
        return updatedResult;
    }, {})
    return updatedResult;
}

console.log(removeVowelKeys(vowelsObj));

You have to use individual .startsWith calls for each character. Also you need to transform the key to lowercase to remove the uppercase keys.

const vowelsObj = {
  alarm: 'hello',
  chip: 100,
  isValid: false,
  Advice: 'Learn it hard',
  onClick: 'make it great again',
}

function removeVowelKeys(object) {
  const num = Object.keys(object);

  for( let i = 0; i < num.length; i++) {
    for (let key in object) {
      const lowercaseKey = key.toLowerCase()
      if (
        lowercaseKey.startsWith('a') || lowercaseKey.startsWith('e')
          || lowercaseKey.startsWith('i') || lowercaseKey.startsWith('o')
          || lowercaseKey.startsWith('u') || lowercaseKey.startsWith('y')
      ) {
        delete object[key];
      }
    }
  }
    return object;
}

console.log(
  removeVowelKeys(vowelsObj)
)

本文标签： nodejsDelete a key under a condition in Javascript objectStack Overflow