# 如何判断字符串包含某个子串
Issue
欢迎在 Gtihub Issue 中回答此问题: Issue 555 (opens new window)
Author
String.prototype.includes();
Author
String.prototype.IndexOf = function (searchValue, fromIndex) {
const string = this;
const len = string.length;
// 默认值为 0
let n = fromIndex | 0;
// 如果 fromIndex 的值小于 0，或者大于 str.length ，那么查找分别从 0 和str.length 开始
let k = n <= 0 ? 0 : n >= len ? len : n;
while (k < len) {
const subStr = string.substring(k, k + searchValue.length);
if (subStr === searchValue) {
return k;
}
k++;
}
return -1;
};
console.log("hello world".IndexOf("ll") + "/" + "hello world".indexOf("ll"));
console.log(
"hello world".IndexOf("ll", -1) + "/" + "hello world".indexOf("ll", -1)
);
console.log(
"hello world".IndexOf("or", -6) + "/" + "hello world".indexOf("or", -6)
);
console.log(
"hello world".IndexOf("wo", 12) + "/" + "hello world".indexOf("wo", 12)
);
Author
function checkStr(string, child) { let res = string.split(child) if (res.length > 1) return true return false }