[JavaScript] 변수타입

다들 알고 있긴 하겠지만

정리차원에서 작성

Javascript typeof()

console.log('nuber type', typeof(100)); console.log('string type', typeof('100')); console.log('boolean type', typeof(true)); console.log('object type', typeof({})); console.log('array type', typeof([])); console.log('function type', typeof(function(){})); console.log('null type', typeof(null)); console.log('undefined type', typeof(aaa)); console.log(isNaN('100aa')); /true console.log(isNaN('100')); /false

형변환

toString()

console.log((4567).toString()); console.log((4567).toString(2)); console.log((4567).toString(8)); console.log((4567).toString(16)); >>> 4567 1000111010111 10727 11d7

String type

var str = 'Hello! this is String'; console.log(str.length); console.log(str.charAt(4)); console.log(str.replace("s", "7")); console.log(str.replace(/s/g, "7")); //전체문자열 검색 console.log(str.replace(/s/gi, "7")); //대소문자 구분안함 console.log(str.replace(/s/gim, "7")); //여러줄 검색 console.log(str.toUpperCase()); console.log(str.toLowerCase());

JSON 직렬 var man = { first : 'one', second : 'two', third : 'three' }; var manStr = JSON.stringify(man); var manObj = JSON.parse(manStr); console.log(man); console.log(manStr); console.log(manObj); > Object {first: "one", second: "two", third: "three"} {"first":"one","second":"two","third":"three"} Object {first: "one", second: "two", third: "three"}

for-in for(var key in man){ console.log(key, man[key]); } >>> first one second two third three

for

for(var i=0; i<10; i++){ console.log('i'+i); } >>> i0 i1 i2 i3 i4 i5 i6 i7 i8 i9

while

var j = 0; while(j<10){ console.log('j'+j); j++; } >>> j0 j1 j2 j3 j4 j5 j6 j7 j8 j9

do~while

var d = 0; do{ console.log('d'+d); d++; }while(d<10) >>> d0 d1 d2 d3 d4 d5 d6 d7 d8 d9