Paige's Journey🎈

WHAT I LEARNED

While my partner and I solve problems together, sometimes I realize that we both need to think simply because we tend to overthink. Fortunately, we get along and I am thankful for my buddy who always answers the questions I ask and help me review what I have learned. I think we can finish what we have to do according to the timeline.

1. CONDITIONAL(조건문)
   • Always need 'Comparison Operator'(비교 연산자)
     
     • > more than
     • < less than
     • >= ane more
     • <= and less
     • === equal
     • !== not equal
   • Result is always 'boolean'(true/false) 

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     if(condition 1) { } else if (condition 2) { } else { }

     c

     • else can be omitted depends on  function.
   • To apply 2 conditions together, use 'Logical Operator'(논리 연산자)
     • AND: &&

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       true && true // true true && false // false false && false //false

       cs

     • OR: ||

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       true || true // true true || false // true false || false //false

       cs

     • NOT: ! (falsy) **memorize

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       if (false) if (null) if(undefined) if (0) if (NaN) if('')

       cs

       • In order to check NaN, use (Number.isNaN(anything)
       • same as Boolean()
         • reference: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Boolean
2. STRING METHODS = IMMUTABLE
   
   • If you do string type + any different type, it becomes string type automatically.
     

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     let str='Paige'; console.log(str +29); // 'Paige29'

     cs

   • If you want to get length,

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     let str='Paige'; console.log(str.length); // 5

     cs

   • If you want to find value,

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     'Paige'.indexOf('Paige'); // 0 'Paige'.indexOf('paige'); // -1 'Paigee'.lastindexOf('a'); // 5

     cs

     • if there is no value, it returns -1
     • lastindexof is you find index from the back and check the order from the front.
     • str.includes(searchValue) does not work at outdated browser and returns as Boolean
   • If you want to seperate,

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     str.split(' ')

     cs

     • Good for CSV
   • If you want to get certain values from the string,

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     str = 'paige'; str.substring(0, 2); // 'pa' str.slice(0, 2); // 'pa'

     cs

     • if start value is negative, it applies as 0.
     • To see difference: reference: https://stackoverflow.com/questions/2243824/what-is-the-difference-between-string-slice-and-string-substring
   • If you want to Uppercase/Lowercase,
     • str.toLowerCase();
     • str.toUpperCase();
   • Math
     • Math.floor(x) = 내림;
     • Math.ceil(x) = 올림;
     • Math.round(x) = 반올림;
     • Math.pow(base, exponent) = 제곱

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       Math.pow(5, 2) = 25;

       cs

     • var1 ** var2 = 제곱

       1

       2 ** 3   // 8

       cs

   • ADDITIONAL
     • trim() : remove space inside string
     • \n : new line

• Need to google more about regular expressions