Checking smooth sentences in JavaScript

We are required to write a JavaScript function that checks whether a sentence is smooth or not. A sentence is smooth when the first letter of each word in the sentence is same as the last letter of its preceding word.

How It Works

A smooth sentence follows this pattern: if word A ends with letter 'x', then word B must start with letter 'x'. For example, "this stringt tries" is smooth because "this" ends with 's' and "stringt" starts with 's', "stringt" ends with 't' and "tries" starts with 't'.

Example

Following is the code ?

const str = 'this stringt tries sto obe esmooth';
const str2 = 'this string is not smooth';
const isSmooth = str => {
    const strArr = str.split(' ');
    for(let i = 0; i < strArr.length; i++){
        if(!strArr[i+1] || strArr[i][strArr[i].length -1] === strArr[i+1][0]){
            continue;
        };
        return false;
    };
    return true;
};
console.log(isSmooth(str));
console.log(isSmooth(str2));

Output

Following is the output in the console ?

true
false

Step-by-Step Breakdown

Let's trace through the algorithm with a clearer example:

const checkSmooth = (sentence) => {
    console.log(`Checking: "${sentence}"`);
    const words = sentence.split(' ');
    
    for(let i = 0; i < words.length - 1; i++){
        const currentWord = words[i];
        const nextWord = words[i + 1];
        const lastChar = currentWord[currentWord.length - 1];
        const firstChar = nextWord[0];
        
        console.log(`"${currentWord}" ends with "${lastChar}", "${nextWord}" starts with "${firstChar}"`);
        
        if(lastChar !== firstChar){
            console.log("Not smooth!");
            return false;
        }
    }
    console.log("Smooth sentence!");
    return true;
};

checkSmooth("cat talks");
console.log("---");
checkSmooth("cat dog");

Checking: "cat talks"
"cat" ends with "t", "talks" starts with "t"
Smooth sentence!
---
Checking: "cat dog"
"cat" ends with "t", "dog" starts with "d"
Not smooth!

Simplified Version

Here's a more readable version of the same function:

const isSmoothSentence = (sentence) => {
    const words = sentence.split(' ');
    
    for(let i = 0; i < words.length - 1; i++){
        const currentWordLastChar = words[i].slice(-1);
        const nextWordFirstChar = words[i + 1][0];
        
        if(currentWordLastChar !== nextWordFirstChar){
            return false;
        }
    }
    return true;
};

// Test cases
console.log(isSmoothSentence("you urban nice elephant"));  // true
console.log(isSmoothSentence("hello orange"));             // false
console.log(isSmoothSentence("single"));                   // true (one word)

true
false
true

Key Points

• Split the sentence into individual words using split(' ')
• Compare the last character of each word with the first character of the next word
• A single word is considered smooth by default
• Return false immediately when a mismatch is found

Conclusion

The smooth sentence checker iterates through word pairs, comparing the last character of one word with the first character of the next. This creates a chain-like pattern where words must connect smoothly.