JS实现---查找字符串中子串的个数

var getStrNumInParentStr = function(parentStr, childStr) {
    if (typeof(parentStr) !== "string" || typeof(childStr) !== "string") {
        return 0;
    }

    if (parentStr.length < childStr.length) {
        return 0;
    }

    let nNum = 0;
    for (let i = 0; i < parentStr.length; i++) {
        let bOkFlag = true;
        let k = i;
        for (let n = 0; n < childStr.length; k++, n++) {
            if (parentStr[k] !== childStr[n]) {
                bOkFlag = false;
                break;
            }
        }

        if (bOkFlag) {
            nNum++;
        }
    }

    return nNum;
}

console.log(findStrNumInParentStr("abcaabcaaaca", "ca"));

输出3