Summary of JavaScript string methods
1. stringObject.charAt()
Function: Return the subscript of the string
var str="这是一串字符串"; console.log(str.charAt(0))//这
2. stringObject.charCodeAt()
Function: The method can return the Unicode encoding of the character at the specified position
var str="这是一串字符串"; console.log(str.charCodeAt(0)) //这=>36825
3.String.fromCharCode()
Function: Pass Unicode encoding returns the corresponding characters
console.log(String.fromCharCode(36825,26159))//这是
Example question: Find whether a string is a number
<body>
<input type="text" />
<input type="button" value="检测" />
<script>
var aInp = document.getElementsByTagName('input');
aInp[1].onclick = function () {
var val = aInp[0].value;
if ( detectNum(val) ) {
alert( '恭喜，'+ val +'全是数字' );
} else {
alert('输入有误');
}
};
function detectNum ( str ) {
var n = 0;
for ( var i=0; i<str.length; i++ ) {
n = str.charCodeAt(i);
if ( n<48 || n>57 )return false;
}
return true;
}
</script>
</body>4. stringObject.indexOf()
Function: This method can return the position where a specified string value first appears in the string.
Parameters: str.indexOf (search value, start searching for subscript), if the string value to be retrieved does not appear, this method returns -1.
Example: Return the subscript where the corresponding character appears
<script>
var str = 'xsxsxscdecdcdxsxsxs';
var num = 0;
var s = 'xs';
var arr = [];
for (; str.indexOf(s, num) != -1;) {
num = str.indexOf(s, num) + s.length
arr.push(num)
}
console.log(arr)
</script>5. stringObject.lastIndexOf()
Function: from back to front Find the position where a specified string value first appears in the string
6. stringObject.substring()
Function: The method is used to extract the string between two characters between specified subscripts.
7. stringObject.toUpperCase()
Function: Convert letters to uppercase
8. stringObject.toLowerCase()
Function: Convert letters to lowercase
9.stringObject.split()
Function: The method is used to split a string into a string array
Parameters: (What Character interception, retaining the number of the array)
Three usages
var str="121314";
str.split("") //[1,2,1,3,1,4];
str.split("1")//[ ,2,3,4];
str.split("",2)//[1,2]
10.arrObject.join()Function: The method is used to put all the elements in the array into a string. Elements are separated by the specified delimiter
Two usages
var arr = [1,2,3];
arr.join("")//123
arr.join("-")//1-2-3Example: Highlight the searched keyword
<input type="text" id="oin" />
<button>按钮</button>
var oin = document.getElementById("oin");
var obtn = document.getElementsByTagName('button')[0];
var str = "arguments对象的长度是由实参个数而不是形参个数决定的。
形参是函数内部重新开辟内存空间存储的变量，但是其与arguments对象
内存空间并不重叠。对于arguments和值都存在的情况下，两者值是同步的
，但是针对其中一个无值的情况下，对于此无值的情形值不会得以同步。
如下代码可以得以验证。";
var h = "";
obtn.onclick = function() {
if (oin.value == "") {
alert("输入为空");
return false
}
var s = oin.value;
if (str.indexOf(s) == -1) {
alert("没有这个数字");
return false
}
var m = '<span style="background-color:red">' + s + '</span>';
str = str.split(s);
h = str.join(m)
document.body.innerHTML=h
}For more JavaScript string method summary related articles, please pay attention to the PHP Chinese website!
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