SOURCE

                
                

function getStringNum() {
    let stringArr = []
    for(let i=0; i< 1000; i++) {
        let list = ''
        for(let j= 0; j< 6; j++) {
            let num = Math.floor(Math.random() * 10) 
            list = list.concat(num)
        }
        if(stringArr.indexOf(list) === -1) {
                stringArr.push(list)
            } else {
                console.log('string:'+list) 
                console.log("stringArr:"+stringArr[stringArr.indexOf(list)])
                i--
        }
    }
    console.log(stringArr.length) 
    return stringArr
}

let arr = getStringNum()