string_to_integer.js

var myAtoi = function (str) {
 // Base condition
 if (!str) {
 return 0;
 }
 // MAX and MIN values for integers
 const INT_MAX = 2147483647;
 const INT_MIN = -2147483648;
 // Trimmed string
 str = str.trim();
 // Counter
 let i = 0;
 // Flag to indicate if the number is negative
 const isNegative = str[0] === '-';
 // Flag to indicate if the number is positive
 const isPositive = str[0] === '+';
 if (isNegative) {
 i++;
 } else if (isPositive) {
 i++;
 }
 // This will store the converted number
 let number = 0;
 // Loop for each numeric character in the string iff numeric characters are leading
 // characters in the string
 while (i < str.length && str[i] >= '0' && str[i] <= '9') {
 number = number * 10 + (str[i] - '0');
 i++;
 }
 // Give back the sign to the converted number
 number = isNegative ? -number : number;
 if (number < INT_MIN) {
 return INT_MIN;
 }
 if (number > INT_MAX) {
 return INT_MAX;
 }
 return number;
};

console.log(myAtoi("42"));
console.log(myAtoi(" -42"));
console.log(myAtoi("4193 with words"));
console.log(myAtoi("words and 987"));
console.log(myAtoi("-91283472332"));
console.log(myAtoi("91283472332"));
console.log(myAtoi("9223372036854775808"));