Replace a string with another string in some conditions

Question

I want to replace the last word of x with y if y includes the last word of x. How can I manage that?

let x ='jaguar lion tiger panda'
let y = 'pandas'

expected result:

'jaguar lion tiger pandas'

if

y = 'cat'

Expected result:

'jaguar lion tiger panda cat'

Code I've tried:

console.log(response)
let before = this.text.split(' ')
console.log(before)
console.log(before.length)
let a = before.slice(before.length-1)
console.log(a)
if (response.data.text[0].includes(a)) {
  let x = (before.slice(0, before.length-1))
  let y = x.replace(',', ' ')
  this.preResult = y.push(response.data.text[0])
} else {
  this.preResult.push(this.text + ' ' + response.data.text[0])

CertainPerformance · Accepted Answer · 2019-01-07 07:09:01Z

3

You can use a regular expression to match the last word, and then carry out your test by checking whether the y includes the word or not. If so, replace the word with y, else replace with the original word concatenated with y:

const x ='jaguar lion tiger panda'

const doReplace = y => x.replace(
  /\S+$/, // match non-space characters, followed by the end of the string
  (word) => (
    y.includes(word)
    ? y
    : word + ' ' + y
  )
);
console.log(doReplace('pandas'));
console.log(doReplace('cat'));

edited Jan 7, 2019 at 7:09

answered Jan 7, 2019 at 6:56

CertainPerformance

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8 Comments

CertainPerformance Over a year ago

Regular expressions are a very powerful and concise tool for string matching and manipulation. They're quite useful for programmers to know. The one used here is super simple, though - \S+ matches non-whitespace characters, and $ matches the end of the string.

user10877669498464651468548513 Over a year ago

and I need to replace panda with pandas because its included in pandas. can you do that also?

CertainPerformance Over a year ago

The code in the answer does that because of the .includes test - press "Run code snippet" to see.

user10877669498464651468548513 Over a year ago

ok thanks 1 last thing i am civil engineer and studying architecture but i love coding at least i think so but its so hard so i turned to design web pages which is easy and fun but i really want to have a good understanding of what happens in background but i dont want to spend so much time on things that are worthless what can you recommend so i research a bit and decide to do or not.. captain

CertainPerformance Over a year ago

It's a really broad field - it's quite opinion-based, so it's up to you.

|

aseferov · Accepted Answer · 2019-01-07 07:05:07Z

0

Another solution:

    let x ='jaguar lion tiger panda'
    let y = 'pandas'
    let splited = x.split(' ')
    let lastWord = splited[splited.length - 1]
    
    if(y.indexOf(lastWord) >= 0){
        splited[splited.length - 1] = y
    }else{
        splited.push(y)
    }
    
    let result = splited.join(' ')
    console.log(result)

answered Jan 7, 2019 at 7:05

aseferov

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1 Comment

user10877669498464651468548513 Over a year ago

I am trying to understand this. this seem to work thanks.

Yan Huang · Accepted Answer · 2019-01-07 07:33:59Z

0

function replaceLastWord(x, y) {
    let result = x.split(' '), lastIndex = (result.length || 1) - 1, lastWord = result[lastIndex]
    result[lastIndex] = y.indexOf(lastWord) !== -1 ?  y : `${lastWord} ${y}`
    return result.join(' ')
}

console.log(replaceLastWord('jaguar lion tiger panda', 'pandas'))
console.log(replaceLastWord('jaguar lion tiger panda', 'cat'))
console.log(replaceLastWord('', 'pandas'))

answered Jan 7, 2019 at 7:33

Yan Huang

412 bronze badges

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