编辑代码

function getIndex(str1:string,str2:string):number{

    let len1:number = str1.length;
    let len2:number = str2.length;
    if(len1 < len2)return -1;

    for(let i = 0;i < str1.length;i++){
        if(i + len2 > len1) break;
        if(str2[0] == str1[i]){
            let count = 1;
            for(let j = 1;j < str2.length;j++){
                if(str2[j] == str1[i + j]){
                    count++;
                }else{
                    break;
                }
            }
            if(count == str2.length)return i;
        }
    }

    return -1;
}
let str1:string = "abcde";
let str2:string = "bcdef";
console.log("======" + getIndex(str1,str2));