Find First Unique

/**

* 计算耗时

*/

function ElapsedTime(cb){

let startTime = new Date().getTime();

cb&&cb();

return new Date().getTime()-startTime;

}

// Find first non-repeating character in a string

function findUnique(str) {

if (!str) return false;

let uniqueArr = str.split('').filter(v=>str.split(v).length<3);

return uniqueArr?uniqueArr[0]:false;

}

/**

* the second method

*/

function findUnique2(str) {

if (!str) return false;

var unique;

for (var i = 0; i < str.length; i++) {

unique = true;

for (var j = 0; j < str.length; j++) {

if (str[i].toLowerCase() == str[j].toLowerCase() && i != j) unique = false;

}

if (unique) return str[i];

}

return false;

}

// 耗时测试 str length more and unique character index more,Elapsed Time will be more

//

let str = 'rrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrddddddddddddddddddddddddddddddddddddddddddddddddddaddddddrrrrrrrrrrrrrrrrrrrrdre';

// let str = 'racecar';

console.time("first:")

console.log(

findUnique(str)

);

console.timeEnd("first:");

console.time("second:")

console.log(

findUnique2(str)

);

console.timeEnd("second:");

//

// console.log("first:\t",

// ElapsedTime(()=>{

// console.log(

// findUnique("racecar")

// );

// })

// )