Javascript Notes

JS References For Future Me:

Just keeping some notes for my squirrel brain. Most of these notes so far are from freeCodeAcademy.

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Parse Integer

The parseInt() function parses a string and returns an integer. Here's an example:

const a = parseInt("007");

The above function converts the string 007 to the integer 7. If the first character in the string can't be converted into a number, then it returns NaN.

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Conditional (Ternary) Operator

The conditional operator, also called the ternary operator, can be used as a one line if-else expression.

The syntax is a ? b : c, where a is the condition, b is the code to run when the condition returns true, and c is the code to run when the condition returns false.

The following function uses an if/else statement to check a condition:

function findGreater(a, b) {
  if(a > b) {
    return "a is greater";
  }
  else {
    return "b is greater or equal";
  }
}

This can be re-written using the conditional operator:

function findGreater(a, b) {
  return a > b ? "a is greater" : "b is greater or equal";
}

Can be applied with multiple conditions:

function findGreaterOrEqual(a, b) {
  return (a === b) ? "a and b are equal" 
    : (a > b) ? "a is greater" 
    : "b is greater";
}

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Recusive Functions (uhguhskdjfh)

function countup(n) {
  if (n < 1) {
    return [];
  } else {
    const countArray = countup(n - 1);
    countArray.push(n);
    return countArray;
  }
}
console.log(countup(5));

The value [1, 2, 3, 4, 5] will be displayed in the console.