Javascript 如何将图像转换为base64 React Native
您能否建议我使用任何库或其他工具将此图像转换为base64的最佳方法: 我第一次认为atributteJavascript 如何将图像转换为base64 React Native,javascript,reactjs,react-native,Javascript,Reactjs,React Native,您能否建议我使用任何库或其他工具将此图像转换为base64的最佳方法: 我第一次认为atributte数据是base64,但我使用了以下功能: function isBase64(str) { if (str ==='' || str.trim() ===''){ return false; } try { return btoa(atob(str)) == str; } catch (err) { return false; }} 因此,当我引入属性data时,如果您愿意,
数据是base64,但我使用了以下功能:
function isBase64(str) {
if (str ==='' || str.trim() ===''){ return false; }
try {
return btoa(atob(str)) == str;
} catch (err) {
return false;
}}
因此,当我引入属性data
时,如果您愿意,此函数将返回我false
。您可以复制下面的代码,并使用这些方法
const chars =
'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=';
const Base64 = {
btoa: (input = '') => {
let str = input;
let output = '';
for (
let block = 0, charCode, i = 0, map = chars;
str.charAt(i | 0) || ((map = '='), i % 1);
output += map.charAt(63 & (block >> (8 - (i % 1) * 8)))
) {
charCode = str.charCodeAt((i += 3 / 4));
if (charCode > 0xff) {
throw new Error(
"'btoa' failed: The string to be encoded contains characters outside of the Latin1 range.",
);
}
block = (block << 8) | charCode;
}
return output;
},
atob: (input = '') => {
let str = input.replace(/[=]+$/, '');
let output = '';
if (str.length % 4 == 1) {
throw new Error(
"'atob' failed: The string to be decoded is not correctly encoded.",
);
}
for (
let bc = 0, bs = 0, buffer, i = 0;
(buffer = str.charAt(i++));
~buffer && ((bs = bc % 4 ? bs * 64 + buffer : buffer), bc++ % 4)
? (output += String.fromCharCode(255 & (bs >> ((-2 * bc) & 6))))
: 0
) {
buffer = chars.indexOf(buffer);
}
return output;
},
};
export default Base64;
常量字符=
‘ABCDEFGHIjklmnopqrstuvwxyzabCDEFGHIjklmnopqrstuvxyz012456789+/=’;
常量Base64={
btoa:(输入=“”)=>{
设str=input;
让输出=“”;
为了(
设block=0,charCode,i=0,map=chars;
str.charAt(i | 0)| |((map='='),i%1);
输出+=映射字符(63&(块>>(8-(i%1)*8)))
) {
charCode=str.charCodeAt((i+=3/4));
如果(字符码>0xff){
抛出新错误(
“'btoa'失败:要编码的字符串包含拉丁1范围以外的字符。”,
);
}
块=(块{
让str=input.replace(/[=]+$/,“”);
让输出=“”;
如果(str.length%4==1){
抛出新错误(
“'atob'失败:要解码的字符串编码不正确。”,
);
}
为了(
设bc=0,bs=0,buffer,i=0;
(buffer=str.charAt(i++);
~buffer&(bs=bc%4?bs*64+buffer:buffer),bc++%4)
?(输出+=String.fromCharCode(255&(bs>>(-2*bc)和6)))
: 0
) {
缓冲区=字符索引(缓冲区);
}
返回输出;
},
};
导出默认Base64;
如果您愿意。您可以复制下面的代码,并使用这些方法
const chars =
'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=';
const Base64 = {
btoa: (input = '') => {
let str = input;
let output = '';
for (
let block = 0, charCode, i = 0, map = chars;
str.charAt(i | 0) || ((map = '='), i % 1);
output += map.charAt(63 & (block >> (8 - (i % 1) * 8)))
) {
charCode = str.charCodeAt((i += 3 / 4));
if (charCode > 0xff) {
throw new Error(
"'btoa' failed: The string to be encoded contains characters outside of the Latin1 range.",
);
}
block = (block << 8) | charCode;
}
return output;
},
atob: (input = '') => {
let str = input.replace(/[=]+$/, '');
let output = '';
if (str.length % 4 == 1) {
throw new Error(
"'atob' failed: The string to be decoded is not correctly encoded.",
);
}
for (
let bc = 0, bs = 0, buffer, i = 0;
(buffer = str.charAt(i++));
~buffer && ((bs = bc % 4 ? bs * 64 + buffer : buffer), bc++ % 4)
? (output += String.fromCharCode(255 & (bs >> ((-2 * bc) & 6))))
: 0
) {
buffer = chars.indexOf(buffer);
}
return output;
},
};
export default Base64;
常量字符=
‘ABCDEFGHIjklmnopqrstuvwxyzabCDEFGHIjklmnopqrstuvxyz012456789+/=’;
常量Base64={
btoa:(输入=“”)=>{
设str=input;
让输出=“”;
为了(
设block=0,charCode,i=0,map=chars;
str.charAt(i | 0)| |((map='='),i%1);
输出+=映射字符(63&(块>>(8-(i%1)*8)))
) {
charCode=str.charCodeAt((i+=3/4));
如果(字符码>0xff){
抛出新错误(
“'btoa'失败:要编码的字符串包含拉丁1范围以外的字符。”,
);
}
块=(块{
让str=input.replace(/[=]+$/,“”);
让输出=“”;
如果(str.length%4==1){
抛出新错误(
“'atob'失败:要解码的字符串编码不正确。”,
);
}
为了(
设bc=0,bs=0,buffer,i=0;
(buffer=str.charAt(i++);
~buffer&(bs=bc%4?bs*64+buffer:buffer),bc++%4)
?(输出+=String.fromCharCode(255&(bs>>(-2*bc)和6)))
: 0
) {
缓冲区=字符索引(缓冲区);
}
返回输出;
},
};
导出默认Base64;
看起来它已经是base64了,这不太好,因为这是对存储、带宽、CPU和内存的浪费。使用base64编码几乎没有实际原因。看起来它已经是base64了,这不太好,因为这是对存储、带宽、CPU和内存的浪费。使用base64的实际原因很少编码。